I don't think that we disagree. I'm not talking about the valuation of the well established companies like spotify, netflix, match.com or even instagram and evernote which I use as examples in the post. These are not the problem, like Amazon was not in the dot-com bubble. I'm talking about the numerous "1 website - 1 app" paradigms that seem to proliferate based on VC backing with ridiculous amounts of money. And from my (very short) experience I've seen how that works and defines the start-ups objectives.
The companies I admire most now, used to be start-ups, however the term tends (for me at least) to get synonymous with something that's easy, temporary and quick money.
Maybe I should write another post talking about the good parts of working in start-ups. The parts that attracted me in the first place. So I can balance my opinion and not generalise so much.
I'll get some corporate experience soon (hopefully) and then I'll be in position to make a small comparison from a totally subjective point of view. After all, who knows, I may miss the start-up environment :)
What you say is true, and I may generalise more than I should, however I don't think you need a phd in astrophysics to see that this is a bubble. Or that's what I think it is, will see, I hope I'm wrong because many of my friends depend on the start-up ecosystem.