Personally, I think the variety of tools is very interesting, and while I like Obsidian and plain markdown file, I do love to see different options in the space with hosted options and different capabilities.
Notion feels like it's got this serious range from individuals up to teams at large enterprises. It's incredibly flexible and configurable and I have to assume that's a big part of it, but it was so interesting to watch it eat away at other things like Confluence over the years. My perspective is probably skewed (and I know Confluence and other are probably still massive and dominant), but I'm surprised such a simple concept is getting so much more software. Or actually, that's probably why it's a space with so much software.