My experience with pretty complicated web development (interactive graphical tools built in webgl, synchronous behavior across hundreds of active clients) was t

My experience with pretty complicated web development (interactive graphical tools built in webgl, synchronous behavior across hundreds of active clients) was that Safari was responsible for massively more bugs than any other browser we dealt with. IE11, Edge, Chrome, Firefox, Chromium, across OSs from a decade back through modern ones - all of those permutations combined. Most commonly we'd see just weird things. Every other browser could handle "render this circle lightly colored, put some text inside it." But random versions of Safari would draw "solid black circle" with illegible text. Update the OS (the only way to update Safari) and the bug goes away. So we wrote work around after work around to make the same code that ran everywhere else run on Safari. And before you ask, all of our devs were on macs, but they weren't running random versions of the os where the bug was present. Or worse, the simulator in xcode wouldn't show the error but it would on a device. At one point over 90% of browser-specific bugs (and almost all customer-reported ones) were due to Safari or Safari mobile, despite making up less than 20% of our traffic. Plus Apple keeps trying to stop people from running test infrastructure of every permutation of os and hardware. It's a nightmare and we just eventually put up a "safari may not work" warning on all our help docs. For our team Safari was worse than ie6, because at least there everyone shared workarounds and knew how to handle the MS foolishness.