"Safari ships new features on a much slower cadence, but they’re usually solid and always perform incredibly well" Well, clearly this person doesn't have much experience with web development... The webengine in iOS is the biggest pile of crap I've ever worked with since IE6. "Oh? You want to click this? OK, let's wait for 300 ms just in case you want to double tap to scroll!" "We finally fixed it, no more delay on cl…
Based on this you either never had to work with IE6 compatibility, or you have a really bad memory. Not least most of what you mention (other than the 300ms delay) is OS level anyhow.
When IE6 came out it was kind of a breath of fresh air... it allowed for a lot of things, and the v4 browsers finally fell off the map. IE 5.0.0 had some hideous bugs on stamped CDs (Office 2000, Windows 2000) that I had to work around for a couple years. IE6 corrected many of them.
Now as things progressed, IE6 became a boat anchor for a long time.. and IE7/8/9 though relatively current at release fell behind very quickly. IE10-11 were also rans in my opinion, and I'm glad most people get to ignore them now.
Nothing compares to dealing with IE4 + NN4 issues... it was truly painful and I'll take what we have today over either. Most people aren't dealing with most of the newer browser features... but for those that are, it can be bad. Safari is the worst actor in the bunch, and they are emphatically not rock solid on that front.