I think that to some degree the lack of certification for browsers (and ditto for Java runtimes back in the days) is what is causing this. Write-once-run-anywhere became Write-once-debug-everywhere.
Java seems to finally start to deliver on this promise though, the last few years have seen quite a bit of improvement. (Still far from perfect though, just the other day I was fighting some corporate website that insisted I install a certain version of Java in a certain browser in order to be allowed access, and it crashed in terrible ways when I finally did gain access).
Imagine that your browser simply wouldn't be allowed on the web until it conformed to a standard. Just like cars aren't allowed to go on the road if they do not conform.
This is unlikely to ever happen for various reasons and I don't think it would be a good thing but the number of broken implementations and hacks-that-became-standards is too large to even count by now.
The default defensive strategy is to pick one browser you know work and select that as the 'standard.'
Not complaining just noting the lock in is an emergent property.