If I sound bitter...well, I really hate phones. My favorite support experiences have never been on the phone. Chat maybe, email maybe, phone never.
THIS. TIMES. A. MILLION.
Call centers put pressure on employees, especially good ones to wrap up calls quickly to keep their numbers high (because shitty policies result in a ton of people calling) meaning that even if you get a rep who legitimately wants to help you, they are punished in their job if they try too hard to do that (or take too long.)
Sidebar; Maybe this is a generational thing, I hate the phone. I hate being on the phone, I hate using the phone. If I have to talk to sales reps I'd much rather do it over email/in person, but not over the phone.
But for the most part I think phone support is a less efficient way to work and actually waste a lot of time both for the customer (waiting in line) and support side. It's expensive for the company but because it's expensive and cumbersome it works as a form of escalation. And given that they are wasting time & money keeping someone on phone might mean they provide some form of support. At least thats what I think.
So it really isn't the best way to support for the most part. But depending on the issue after its triaged, tracked through a issue tracker sometimes a proper phone/conference call might actually be helpful.