I too discovered sizecoding through dwitter way past the original demoscene era, but I think codegolfing with javascript scratches a similar CS/math/language tricks itch. Had a lot of fun with dwitter, and it definitely helped me feel more fluent in coding for work, just from all the practice even though optimizing 140bytes and SWE-ing multiple thousand line files are two different niches at first glance.

Which is, in fact, a demotool made by sceners and released at a party (check their about!) Just like Shadertoy and others :)