What evidence is there that anything Chrome specific was used? Safari’s WebGL support has come later than others, and there are reports of WebGL being slower on Safari than Chrome, for example https://developer.apple.com/forums/thread/696821 It’s possible your incredulity maybe should be directed towards Safari and not someone trying to do their best?
Despite using firefox and wantind cross browser projects I think the learning involved in browser compatibility is a LOT less interesting then about the math behind animation.
You won’t find many people who consider this “valid” criticism. This is a pet project for educational purposes and you’re complaining because they’re not equivalently efficient on every platform.
`Meh. Just because "it's out of scope of what I planned" doesn't mean that with a few critiques/pointers along the way that it couldn't be better.
I understand the "let's do this for the lulz and see what happens/learns/etc", but once you feel like it is "good enough" that you post it to the public (for let's face it, publicity/showing off/self-promotion), you HAVE to expect that some people might think it isn't good enough and here's some ideas to make it better.
That's not to say that what was posted is shite. It's just with a bit more...it could be even more.