Not many are using gigabit upstream, but Spectrum’s 300 megabit down plans in my area come with like 20 megabit up. I’d get noticeable stutter in calls if I browsed the web during one.

Thankfully synchronous gigabit fiber came this year.

If I take a video on my phone and sync it to the cloud that's easily more than that. And if that takes up the whole 10 Mbit, video calls get unusable.