Some of their employees are not good. Some of them disrupt the others. Some of them are negative. They make the other talented employees not want to work at the company. So you remove them. The remainder of the company is then happier and produces better results.

Disruptive maybe, but negative?

Some people became negative because they saw problems they can't resolve by themselves. Maybe don't fire this kind of people?

But, well, it seems some companies just don't care.

The problem is that negativity goes nowhere. There's nothing special about raising a problem until you have a realistic proposal about how to address it either fully or partially.