The answer is simply that yes Safari breaks websites, but users are happy to make that tradeoff.
It's common knowledge among web developers that browsers aggressively throttle background tabs so anybody who is designing a website that depends on it is misguided.
I don't hear anybody complaining about Safari being too aggressive with background tabs, I do hear people complaining that Firefox uses too much battery. So I think Firefox should be more aggressive.
A poll of your friends may not constitute adequate data for making such decisions. We know for sure that techie-people and friends-of-techie-people are qualitatively different to the mass market.
These tradeoffs may also be different for different browsers. E.g. if you're Apple, perhaps breaking Web sites isn't a big deal since on iOS Safari is entrenched by fiat, and if users switch from Web apps to native apps, so much the better for Apple. For Mozilla that calculation works out differently.
Generally speaking "site X breaks in Firefox, works in Chrome" is a good way for Mozilla to lose market share.
Haven't people been complaining that youtube will randomly stop playing in the background on safari? I'm not so sure users are happy about that as you say.
It's common knowledge among web developers that browsers aggressively throttle background tabs so anybody who is designing a website that depends on it is misguided.
I don't hear anybody complaining about Safari being too aggressive with background tabs, I do hear people complaining that Firefox uses too much battery. So I think Firefox should be more aggressive.