I'm not sure how useful the edits are in practice but I've contributed hundreds of questions about wheelchair-accessible sidewalks, street lighting etc and hope that this is helping some people make better navigation decisions.
It depends on who you ask!
For me, things like opening hours or paid parking indications are very helpful.
My girlfriend was doing some running training a while ago and in summer during the day it can be quite hot. But at night, how do you know which roads are lit if you want to plan your route ahead of time to have the right distance? Easy: OSM has the data, OsmAnd and others can display it... except our area had almost no coverage at all. StreetComplete made it super easy for me to map that, so now it's there. She stopped running in the meantime but... hopefully the next person can make use of it, the data is there to stay :)
For the wheelchair questions, there is of course another audience that might like to plan routes without finding inaccessible steps in the middle.
I can also imagine if you drive trucks, having good weight/width/height limit data is also useful. Right now I think this data is quite incomplete (though I didn't do a comprehensive study) and I have no idea what those companies use instead (maybe they just drive a route before sending trucks down it?), but at some point a free worldwide uniform dataset is going to be easier than whatever they use now.
Made me laugh!
Thanks a lot for sharing. These are all great usecases and it is good to hear people make use of that. I didn't have the need for it, and while I can see the intrinsic value in having this data widely available in OSM the fact people do actually use it for something makes it more "real"!.
Heavily depends on a question, some are quite niche.
But even backrest quest has some use - thanks to it I detected and deleted some no longer existing benches.
See comments in https://github.com/streetcomplete/StreetComplete/blob/master... and below for some additional context.
And note that some not-yet-used data will be more likely to become used as OSM coverage improves!
For those not aware: On https://www.openstreetmap.org/ you can leave comments on the map, so called Notes (https://wiki.openstreetmap.org/wiki/Notes). It's like bug reports but on a map, with comment thread. Local mappers look at those. Or that is the idea, I've seen notes open years and others resolved within hours.
The answers with new information are useful for local mappers, even "this shop no longer exists" answer (examples https://www.openstreetmap.org/note/2659780 , https://www.openstreetmap.org/note/2641050) when asked about opening times. Many notes need a local mapper to verify (visit the place, find secondary information).