> It’s been a whole year since the pandemic started and video calls are still terrible.

Because it's hard. Just going through the list in the article:

> Use a cable to connect to the Internet

Difficult if your house isn't wired for ethernet and the modem is in an inconvenient spot, or in a room which contradicts tip #4. Do you let a long cable drift along the floor?

Powerlines will work in some houses, but not others, and can occasionally introduce their own connectivity problems.

> Make sure your upload speed is >3 Mbps

And if your ISP doesn't offer that much upload bandwidth, well then I guess you're SOL.