Everyone already complains that browsers are too bloated and now you want to have every browser support sortable tables when a single, simple JS file would work?
>single, simple JS file
It's all fine and dandy until marketing bros decide to shove all kinds of shady modals into that JS file. The JS side is not exclusive to trivial interactivity.
The overwhelming majority of web pages are static documents, and it's a document format, so basic document primitives make sense. Same with something like line charts or pie charts. Bloat is things like USB APIs that present obnoxious security surfaces.