That is, as so many things with tech, a matter of giving proper UI for humans as much priority as the feature itself.
It would be solved with something as simple as a "Privacy Blocks" drop-down menu that was prominently shown in the browser, that could visually warn about which feature is being accessed by a website (WebGL, UTC time, scripting...), and that let the user enable/disable that feature in that specific website with just 1 click.
A bit of telemetry (albeit kinda contradictory in this case) would allow to collect data on which sites tend to require which permissions, and proactively warn the users, like "Hey it seems most users of Google Calendar .com tend to disable time clock privacy; would you like to do so too?", that'd remove a lot of worries from users upon accessing an important site and not knowing which privacy settings might be breaking it.
It would be solved with something as simple as a "Privacy Blocks" drop-down menu that was prominently shown in the browser, that could visually warn about which feature is being accessed by a website (WebGL, UTC time, scripting...), and that let the user enable/disable that feature in that specific website with just 1 click.
A bit of telemetry (albeit kinda contradictory in this case) would allow to collect data on which sites tend to require which permissions, and proactively warn the users, like "Hey it seems most users of Google Calendar .com tend to disable time clock privacy; would you like to do so too?", that'd remove a lot of worries from users upon accessing an important site and not knowing which privacy settings might be breaking it.