I could easily take each of these points and flip them around to "prove" why statups shouldn't hire Jr. developers. Especially in regard to new developers being ready, willing, and eager to hop onto the latest trend... regardless of whether or not that trend actually fits the needs of the organization.

One can group developers into many categories, some useful, some not. Here you've assigned a bunch of traits to developers based primarily on age, when in actuality, and to pick just one example, I could group them into those that embrace change, and those that do not.

Sure, some older developers might not want to pick up something new, but younger dev's too can get locked in into the technology that they've chosen, based on its "obvious" superiority. Not to mention that a given piece of technology, like, say, React, might have been the only toolset they've ever used through their extensive 2-year-long careers.

I programmed mainframes, minicomputers, controllers, PCs, Macs, servers, front-ends, and, currently, iOS apps. Dozens of platforms and dozens of languages. One thing I've learned is that, in tech, the only constant is change.

One can embrace it, or not. If not, then your skillset will gradually fall by the wayside. Doesn't matter if you're young or old.