Because of these shitty corporate companies that don't give a shit about their employees, the well is now poisoned for companies that do care especially smaller ones. Employees don't want to give their best anymore because they are burnt elsewhere and they become unemployable at smaller companies. It is a sad state of affairs.

I've worked at the full spectrum from great to terrible (and eventually one that went legally fraudulent) companies.

You're right that there can be a problem at small companies when you hire someone out of a toxic company. Some people love the fresh start and are so happy to finally be in a healthy environment that they thrive.

Some people are so broken from toxic previous employers that they can't adapt. We hired a lot of people out of a competitive Big Tech office and it was probably a 50/50 flip of the coin if they were going to be great to work with or toxic political monsters. I had to have so many difficult conversations with people who could only see their coworkers and other teams as competitors who had to be defeated that I nearly had a prepared speech on the topic. The politics and attempted backstabbing was insane. It was also weird that they thought it was going to work at a small company where we knew the people they were trying to backstab for years.