It’s a niche tool for people with disabilities... but that’s not to say you can’t use it being fully able.
There was an HN post from a hacker about being a software engineer while having a degenerative muscle condition that makes it hard to type.
I’m tempted to support just to get the full version.
Here’s the HN entry: https://news.ycombinator.com/item?id=24846887
Certainly looks interesting, and seems he has 384 patreon supporters so there's definitely something there.