1. I have to run OBS separately, before gaming or when I ant to record something while I am playing already.
2. Configuration of the settings. While I found good settings, its still complicated for most people. Especially on Wayland (a Linux thing).
3. When I want to capture a game, I have to specifically run the game and select in OBS to capture this window. Or capture entire screen.
4. I still can't use AV1 for recording, but I think that I managed to set VAAPI recording set to my GPU? I am not 100% sure.
5. The flexibility of recording and organization in the way Steam does it is way superior to any external software and custom configuration of it. With OBS I have to rename files and organize things manually, while these are done automatically for each game in Steam.
6. Besides Steam has background recording too, not just on demand manual recording on button press. Think of Nividias Shadowplay. With OBS I have to start end end recording manually.
7. While we play we can add specific markers to the timeline with hotkeys. OBS doesn't have that.

OBS is clunky and complicated to me. The Canvas and Output resolutions are separate, which confuses me the hell out of it. I only experimented with some settings so far to record gameplay (after my new PC installation) and need to see how this works out. But if I change settings to record something different, then I have to configure it again to record gameplay. Also to use Hotkeys, I have to allow hotkeys to be used globally in my system (which I don't want to otherwise). Because of Wayland and how it works.

All in all its must simpler and superior to do this in Steam itself now. For other use cases, I will still keep OBS, its not bad, just not straightforward for daily game recordings. But I can add other software and games to Steam and can use it with Steam Recording too (if the overlay works there).