I am part of Management in my company. We explicitly maintain a list of key people in the company we don’t want to lose. The truth is that just a few people are what makes a company. Lose them and you are in trouble. Some companies don’t seem to understand that, but perhaps after a certain size, it doesn’t matter anymore! The machinery just keeps turning.

I met a guy this happened to. He got a special award within the company, asked for a bit of equity, didn't get it, in fact got blacklisted and booted out.

Luckily for him it worked out very very nicely.

Well how can they have the time or resources to invest in retaining talent? They're busy hiring more interns, where one could be an "attention all you need" research paper writer, who could set up the next stage of innovation which you'll completely miss if you do not get anyone.

Yes. The intent is not to retain them or keep them happy, it's just to prevent them from doing inventive work for anyone else.