I know I'll be an outlier here, but I'm going to say it anyway: Total BS!
Browser technology in general* is horrible and its design is atrocious. It's lack of capability and the bureaucracy the standards committee impose only serve to limit real creativity and drown anyone who tries a novel approach to anything.
It's absurd to make the statement "browsers provide what users need". That's entirely subjective and users can't know what's even possible when developers are prevented from providing better options.
Scrolljacking is the perfect example of this. People don't implement scrolljacking because the scrollbars do everything that's required of them they do it because browser tech sucks and the developer is then forced to make trade-offs.
We shouldn't be telling developers not to scrolljack (which only serves to stifle creativity) we should be telling browsers to smarten up and lessen the trade-offs developers are required to make.