There's no open source standard. No LibreOffice or Krita of notetaking.
They all only have a small subset of features one might want.
And yet they are critical infrastructure for people's entire life. It's a pretty exciting space.
For those who just want a generic and easy to use app like OneNote, they’re not going to find it in Obsidian.
That's not an accurate statement. Obsidian can literally be as simple as one wants it to be, or as sophisticated in virtually any direction. The culty "Zettelkasten" emphasis is entirely coming from the community and can be totally ignored (as I do).
So for me as a long-time Mac user (and rather less long-time iPhone/iPad user), the realistic benchmark is Apple Notes: it is simplistic, fast, well-integrated and ubiquitous. It has just enough features to be useful and not enough features to be opinionated.
Absent the iPhone side of things, I'd likely use Simplenote.
I hope, at some point, something akin to another enhanced subset of Markdown will become the de-facto standard.
There's UTF-8 and JPEG.