Height, weight, hair color and year of birth aren't PII, but if you combine them, you're getting pretty close to identifying individuals, it's a behavioral finger print - and though I have no idea if it holds true in general, I'd assume that there's even a strong transfer across devices (a power user scrolls faster on both mobile and desktop).
Is there a way to really solve it? It seems to me that all you actually can do is up the ante, make it harder to do, but with full browser control, it'll be hard to lock them out. And if I'm looking at the behavior of users on my site, I can probably build pretty good replay users that visit the site you're protecting. I remember the "attack" on IRC channels back in the day where you'd join a bunch of bot users that would then have a conversation that is replayed from another channel (possibly in a different language), so timing, interaction etc looked very real (though they may seem a bit rude for not reacting to other people).