Interesting, in my Arc browser, I just tried File -> open -> upload -> blah.md and it does seem to render fine. This exact thing did not work a few weeks ago, meaning the various header markers etc showed up as raw "##" etc, and I had to further select something like "open as new doc" to finally make it look good.
Obsidian has become almost an operating system for working with markdown. Its Live View / Edit mode is excellent (WYSIWYG) and its ability to accept pasted content and handle it appropriately is good and getting better. Its plugin/extension ecosystem is robust (and has a low barrier to entry), and now that it has a CLI I expect to see an acceleration of clever workflows and integrations.
No affiliation, just a very happy ~early adopter and daily user.
Wow, that's a strong opinion and harsh words that come across as really entitled, and probably unfair. From my PoV, they're a tiny, scrappy, transparent and likeable company who built and maintain a fantastic software application that radically improved ~everything about my daily workflow and PKM. I get more value out of Obsidian in a day than most other apps in their entire lifespan. The core app is free! They have to eat. I'd probably throw $ at them even if they didn't charge a few bucks / month for Sync. (Which works flawlessly.) Sure it'd be cool if you could self-host their Sync module -- but many Obsidian users use other DIY approaches for sync; in the end it's markdown files on a local disk, do with it what you will.