You're point about testability is a good one that I feel is often missed. Trying to test functions in OOP code is often impossible because they presuppose some state in the "object" and if it's not initialized properly, it doesn't work. Then they also often make side effects. So you end up building a huge test harness to build up some state, run one test, and tear it all back down again only to rebuild it from scratch for the next test. It's doable of course, but it's easy for a simple CRUD app to have a 15 minute test suite and for tests to become flaky because of some unexpected state change done in some unrelated test on the other side of the code base. That's a special form of hell