Javascript was instantly a hit from the day it was released, and it grew from there.
XSLT never took off. Ever. It has never been a major force on the web, not even for five minutes. Even during the "XML all the things!" phase of the software engineering world, with every tailwind it would ever had, it was never a serious player.
There was, at no point, any reason to invest in it any farther.
Moreover, even if you push a button and rewrite history so that even so it was heavily invested in anyhow, I see no reason to believe it would have ever been a major force in that alternate history either. I would personally contend that it has always been a bad idea, and if anything, it has been unduly propped up by the browsers and overinvested in as it is. But perhaps less inflammatorily and more objectively, it has always been a foreign paradigm that most programmers have no experience in, and this was even more true in the "XML all the things!" era which predates the initial Haskell burst that pushed FP forward by a good solid decade, and the prospects of it ever being popular were never all that great.
XSLT never took off. Ever. It has never been a major force on the web, not even for five minutes. Even during the "XML all the things!" phase of the software engineering world, with every tailwind it would ever had, it was never a serious player.
There was, at no point, any reason to invest in it any farther.
Moreover, even if you push a button and rewrite history so that even so it was heavily invested in anyhow, I see no reason to believe it would have ever been a major force in that alternate history either. I would personally contend that it has always been a bad idea, and if anything, it has been unduly propped up by the browsers and overinvested in as it is. But perhaps less inflammatorily and more objectively, it has always been a foreign paradigm that most programmers have no experience in, and this was even more true in the "XML all the things!" era which predates the initial Haskell burst that pushed FP forward by a good solid decade, and the prospects of it ever being popular were never all that great.