That is an inaccurate description of dark matter. It was originally theorized to explain why the rotation curves of galaxies did not match the mass distribution of the observable mass in those galaxies. There were several ideas for what form that mass could take, but many of them have been eliminated as possibilities (black holes, stellar objects that are too dim to observe, etc.).
There have been several independent observations that are explained by dark matter, and it's not like the theory for dark matter was specifically changed to accommodate those observations. The most well-known is around gravitational lensing, as the amount of observable mass in clusters of galaxies does not match the amount of distortion that we observe. There are however several others. This kind of independent validation of a theory from other angles is a textbook case of how theories are validated - they are proposed to explain one thing, but turn out to also explain other things.
MOND meanwhile has a much tougher time explaining the other observational evidence. It has had to be extensively patched to fit the other cases. Additionally, as noted elsewhere in the comments, neutrinos are not dissimilar to dark matter. Both are forms of matter that it do not interact electromagnetically, making them all but impossible to detect directly. Theorizing that there is more than one such type of particle is not very much of a stretch. Taking that into account, MOND seems to be a much more complex solution than just having another type of matter with properties similar to those we have already seen.
Almost all of the skepticism around dark matter comes from outside of the scientific community, and I think both the name and it being lumped in with dark energy (which is just a placeholder, not an actual validated theory) are part of what contributes to this. While obviously the consequences of this skepticism are significantly less dire, the reasons for it seem pretty similar to those of climate change skeptics - primarily tied to human intuition.
My understanding is that an entry in the card table is set when an object in young generation is allocated that is referenced by something in the old generation. An entry in the card table corresponds to a 512 byte segment of memory in the old generation. Thus, the cost imposed by this would be based on how many distinct 512 byte segments of the old generation reference any objects in the young generation.
If you have a web service that mostly consists of some baseline of long-lived objects and many short-lived objects used for fulfilling requests, I would expect to have relatively few GC roots. At that point, if you assume that you have a consistent request rate, I would expect the number of reachable objects in the young generation to remain constant regardless of the size of the young generation, and the number of GC roots should also remain constant. Based on that, increasing the young generation size would then decrease the frequency of young generation garbage collection, reduce the probability of survivors getting promoted to old generation, and have no effect on the time it takes to do young generation garbage collection. There certainly applications that have different behavior when the old generation is less static, but I would think for this use case the new generation size should be as big as it can be.
If something I've said is incorrect or incomplete, I'm anxious to know. There are relatively few well-written explanations of how Java garbage collection works, so it is difficult to have confidence regarding it without a lot of practical experience as you have said.
I think the thing to keep in mind is that Amazon is a company of extremes. There are parts of the company, maybe a large fraction of the company, that are at least in the direction of what you described (although the drug dealing bit is a one-off if it’s true). However, there also parts where there are many people that have been at the company over a decade (namely AWS). I’ve been working here a few years, and I won’t deny that I got lucky with what team I work for, but outside of maybe being a college hire you should really get some idea of what you’ll be working on and who you’ll be working with before you actually work there. I work on things that are really interesting to me, and yeah, there are some crappy parts like oncall and occasional bad management, but the first gradually improves and the second tends to resolve itself.
Also, my experience with people leaving/coming in my part of AWS is that people who leave the company entirely almost exclusively weren’t doing very well. The more experienced people tend to just transfer elsewhere within AWS. Also, Amazon hires a huge number of ex-Microsoft employees, whereas I only know of one person personally who left to go to Microsoft.
There have been several independent observations that are explained by dark matter, and it's not like the theory for dark matter was specifically changed to accommodate those observations. The most well-known is around gravitational lensing, as the amount of observable mass in clusters of galaxies does not match the amount of distortion that we observe. There are however several others. This kind of independent validation of a theory from other angles is a textbook case of how theories are validated - they are proposed to explain one thing, but turn out to also explain other things.
MOND meanwhile has a much tougher time explaining the other observational evidence. It has had to be extensively patched to fit the other cases. Additionally, as noted elsewhere in the comments, neutrinos are not dissimilar to dark matter. Both are forms of matter that it do not interact electromagnetically, making them all but impossible to detect directly. Theorizing that there is more than one such type of particle is not very much of a stretch. Taking that into account, MOND seems to be a much more complex solution than just having another type of matter with properties similar to those we have already seen.
Almost all of the skepticism around dark matter comes from outside of the scientific community, and I think both the name and it being lumped in with dark energy (which is just a placeholder, not an actual validated theory) are part of what contributes to this. While obviously the consequences of this skepticism are significantly less dire, the reasons for it seem pretty similar to those of climate change skeptics - primarily tied to human intuition.