I think the quote on the app page says it all: bikes, not aircraft carriers. I use Obsidian, and really like it, but it’s an aircraft carrier. Bike is, well, a bike.
I might, after using it, find that it’s just too simple and I need an aircraft carrier after all, but my impression right now is that the Obsidian-vs-Bike comparison is not 1:1 enough to be fair.
A cargo bike perhaps, but if you call Obsidian an aircraft carrier already then there aren't much metaphores left for software which does way more and is (feels) slower than Obsidian.