Some of this is due to Scrum but other parts of it would still exist in these companies even if they changed to Kanban. I think the problem is the kinds of companies that have these processes can't find an alternative. The companies I've worked at where it was like this were all sales-driven enterprise software where deadlines are the focus and being able to tell a customer it'll be there in X months was viewed as critical. So they put all of these processes in place to make sure they can consistently hit deadlines even if it means slowing everything down to a halt. It still doesn't work that well but just removing the process isn't going to work without changing how the rest of the company operates too.