[hollerith]

If that is true, then why did the telcos rapidly move the entire backbone of the telephone network to IP in the 1990s?

And why are they trying to persuade regulators to let them get rid of the remaining (peripheral) part of the old circuit-switched network, i.e., to phase out old-school telephone hardware, requiring all customers to have IP phone hardware?

[musicale]

They moved to IP because it was improving faster in speed and commoditization vs. ATM. But in order to make it work, they had to figure out how to make QoS work on IP networks, which wasn't easy. It still isn't easy (see: crappy zoom calls.)

Modern circuit switched networks use optics rather than the legacy copper circuits which date back to telegraphy.

[mulmen]

You can criticize something and still select it as the best option. I do this daily with Apple. If you can’t find a flaw in a technical solution you probably aren’t looking close enough.

[kragen]

Packet switching is cheaper; even though it can't make any guarantees about latency and bandwidth the way circuit switching could, it uses scarce long-haul bandwidth more efficiently. I regularly see people falling off video calls, like, multiple times a week. So, in some ways, it's a worse product, but costs much less.