I find things like TextSniper to be more useful than this functionality, which has been in iOS and MacOS for a little bit. I use it more on hypothetically selectable elements that for whatever DOM-related reason aren't selectable than I use it on text in images.
In an "X is just Y" comparison, a good heuristic to determine whether someone is being a human being is to ask whether the comparison reduces the humanity out of the concept. This kind of thing is sociopathic.
I don't get how a pro photo app is supposed to be mobile-only and subscription-gated. One of the greatest things about flickr is that I can embed it almost anywhere, even hotlinking on my blog or on forums, and anyone, anywhere can see it on any device. (And if I pay, they can see a 6k version, served on the web, not through a download link.) I am really, really into photography but I do not have any interest in viewing image galleries on my phone when I have a 27" iMac 5k and Flickr shows me over a decade of photos collected from every type of photography enthusiast.
The thing with Markdown is that it does most of what you need to do with it, until it doesn't, when you can bring Pandoc to bear and put full-on LaTeX in your Markdown and it will render it however you want. I wrote a dissertation this way with inlined Rmarkdown code. It was great.