[squeeeeeeeeeee]

> you're more likely to have been exposed to bad OO code than any other type simply because there's more of it

That's certainly true, but as someone who routinely has to go in and bugfix/maintain classes contaning thousands of lines of code (sometimes in themselves, more often collectively in their inheritance hierarchies), the simple presence of extensively used member variables often is a massive cognitive load. I'm not claiming that I'm some rockstar programmer who knows better, but from my experience working with other programmers, member variables might as well be called global variables.

tl;dr: Mutation, mutation everywhere.