Also ironic given that most people have adopted some of that "broken CSS box model" in their CSS.

    box-sizing: border-box;

Now there were many other problems but I'm not sure people appreciate how such features eventually got standardized. Similar issues happened around DOM serialization with APIs like innerHTML, which Netscape refused to adopt because of "series of pointing at standards". Developers ended up adopting the idea and it was later standardized. XHR is another case. There are many more.

In the case of Safari, I can think of canvas, touch (love or hate it vs pointer events it was before any of the alternatives), DPI independence, &c.

It's some of these quirks that seems to show how newer web standards might be rushed through by increasingly aggressive vendor involvement. Apple hasn't changed all that much from when it first released Safari. It's only our expectations for the pace of new additions that has.

IE5.5 had the broken box model. IE6 used the standard box model if the site had a recognized !DOCTYPE and the 5.5 model if it didn't.

Web dev was "fun" in the early 2000s.

Also console.log and javascript debuggers didn't exist. Working with complex JS got really interesting really quickly.

Or that Safari has no support for WebRTC.

It's so easy to be cavalier about random popular facts. I would love for someone to go back and load up the alternative browsers available at the time on some vms and take stock of their featuresets. Factoring in popularity at the time I'm pretty sure not much would have changed.