I've worked as an employee, a contractor, and owned my own firm and hired. Seen all sides.
Until the last few years, the idea of hours and hours of interviews wasn't a thing. I interviewed at IBM and was hired after two, 1 hour interviews. One of those over the phone.
I can't even envision what these interviews are all for. It feels like people attempting over the top risk management, without really scoping the risk. It feels quite disorganized.
My experience more closely matches yours, but I've also done the multiple rounds of painful interviews.
I do find that the latter can be explained by care and concern, and also by organization chaos and poor boundaries. It's hard to tell until you're in them, but I try to avoid the latter whenever I can.
As another commenter mentioned - I now respect companies that take their time in hiring. The last thing I want is to jump on with some company that will hire anyone. But there is an element of respect - if you're just duplicating questions and wasting my time? GTFO here.
Well, bullshit actually. When I went to Sun in 1996, I was flown out for a full day of interviews (9 hours!) plus both lunch and dinner. (And this was true for more or less every company I interviewed with.)
I'm not sure why people are indexing so hard on the interviews, as we matriculate very few candidates into conversations; if you want to complain about something, complain about the written nature of our hiring process.[0]
I firmly believe it's because someone getting fired, for poor performance, is a huge deal now.
Where I am, exposing someones poor performance is more of an exhibition in the failure of the hiring process and all involved. So, you just keep the under-performers around.