Just tried it now and I found the experience incredibly easy:
On desktop, right click on the map and choose "Add a missing place." On mobile, long-press to drop a pin, then scroll down to "Add a missing place."
Does OSM require installing a parallel app store to add a park bench? Sounds like a UX-killer :/
Just tried it on mobile and that is nice and easy, especially if you want to add a business. Not sure how you add a bench that way as I couldn't see the option, but I might be looking in the wrong place.
You're right though, installing another app store is a non starter.
To add new features I have to use SCEE, which is more nerdy mainly because it involves using FDroid to install it. But I've no idea how to add, say a park bench to Google Maps.