That's like saying "you do not need oracle to use your bytes on disk". I may be mistaken but doesn't obsidian provide a ton of functionality on top of markdown?
No, just a little bit. Your docs remain 98% compatible with other Markdown editors. The functionality is mainly around a.) better UI for editing Markdown, b.) plugin ecosystem (optional), c.) paid sync (optional, and achievable otherwise e.g. SyncThing, your own rsync script, etc), and d.) optional (and very bad) "publish-as-a-website" feature.
The plugins are no small thing though. I replaced Anki with a spaced repetition plugin, now my notes can be flashcards and I don't need to maintain two separate apps.
Also the UI for search and navigation is much better than just a collection of Markdown files. I rolled my own note system using Markdown before this. Obsidian is way better.
If you only use standard Markdown. But the advocacy often focuses on DataView and a thousand other features that are simply not available without Obsidian.
True, but it seems very obvious that if you add a bunch of plugin dependencies (or even one), you are deliberately choosing to forego "standard" Markdown (there's actually no such thing, but roughly speaking).
That's why they're plugins.
I do use the Excalidraw plugin, but nothing much else, and that is why I have an easy time making my Obsidian notes web-accessible (currently, via SilverBullet, but any tool that makes markdown web-editable will work — as long as you don't go nuts with plugins, that is).
Having said that, I think the reason Obsidian "failed" — to the extent that Notion and some others have massively more adoption amongst organizations larger than me and my gray beard – is that they failed to combine their (super awesome) files-and-folders approach with a web editable solution.
They thought - obviously wrongly, in hindsight — that web accessible would be enough.
It's not. It's the 10%, Notion etc cover the 90% (but with fairly bad tradeoffs, they have export and it works, but you can't easily interop with your data where it lives).
But I've had such an easy time making my Obsidian web-editable that I suspect in a few minutes (or months) Obsidian will be like heyyyyy... edit yo vault via web yo — and for free! and then we will all be like woo Obsidian boo Notion!!