I toggle it on and off with a keyboard shortcut on a rare occasion colors are hard to read for me. Mostly use it on my phone actually (it's a triple click of the lock button on my iPhone). There are shortcuts on Windows and MacOS too. Doesn't seem like it would be too inconvenient for someone that actually suffers from color blindness or a site issue, I would expect they'd run into the issue more commonly than me and would then know how to solve it for themselves.

A lot more inconvenient for others to have to pick colors that satisfy all potential site issues, which is primarily why I think it should be an OS solution rather than an individual creator's responsibility. It's not that I don't care about those with the site issue, it's purely about who is responsible for creating a reasonable solution. And honestly, there's no way every creator is going to study accessibility and so it's just a never ending uphill battle. If you had a tool in your system already that could help, why wouldn't you use it?