Interestingly, game development was a major factor in the origin of QBJS. It grew out of an effort to build a 2D game engine for QB64 (GX). One of the experimental features that I included was an "Export to Web" option. The goal of this feature was to make it easy to share games online without needing players to download an executable. As it turned out though, there was more initial interest in this feature than in the game engine as a whole. Long story short, QBJS spun off as its own project with the larger goal of providing QBasic in the browser with as much compatibility as feasible with QB4.5 and QB64 while providing near-native performance.
Regarding point 5 of your post, I definitely think that if someone wants to create tools for games, the best way to know how to build those tools and to know what game devs need... is to make games!