None of this is due to "modern web development". It's just about a dev not checking reasonable asset size before deploying/compiling, that has happened in web, game-dev, desktop apps, server containers, etc. etc.

This should be an SVG (a few kb after proper compression) or if properly made as a PNG it'd probably be in 20-ish kb.

The dev not having the common sense to check file size and apparently not realising that the PNG format was being grossly misused for this purpose (by not even having a single tone of white for the J and the corners, let alone for the blue background) is modern web development.