That SVG can execute Javascript also used to be well known, back when SVG was considered the future replacement to Flash. I even remember some websites that were just one handcrafted SVG. And browsers deciding not to execute these scripts when you load an SVG via an <img> tag was a big deal.

Of course SVG didn't become the Flash replacement everyone hoped for, so that knowledge seems to have become more obscure. The same probably happened to knowledge about javascript links after frameworks like react made event handlers the more convenient alternative.