Weird, i just ran an old gulp based bundled project using bun without issues. I think there are problems with web tooling fragmentation but this argument sounds contrived as an attack the web platform. Js code from 10+ years ago runs without modification today which was the point. Tooling changes over time ofc.
My old uni android apps still work on android last i checked. With a recompilation my ios apps work on ios too.
However, with absolutely zero work, ALL of my web stuff across all time works just like it used to even the angular 1 stuff.
It is why i love web so much. It is the ultimate distribution platform with so little needless churn.