My phone still didn't come with a functional paint or notepad apps. Google docs is a horrible experience on phones (but at least it works now - a few years ago it was straight up unusable).
And you're telling me that this is the only computing platform for a lot of people? How is everything still so unusable about it then?
My experience tells me that everything mobile is basically an afterthought outside of a few dozen websites and I guess phone games.
Note-taking works fine, in Google Keep, Apple Notes, or some other cloud equivalent. Yup, your data is in the cloud and owned by one of those tech megacorps, but most people just don't care.
Basic photo editing works okay too, in Google Photos, Apple Photos, etc. Ditto the cloud stuff.
What really makes most desktop users outliers is caring about, or even being aware at all of the concept of, actually owning your own data versus trusting cloud providers for everything.
If I need to take some notes I can't even imagine going to search through a store to find a note taking application since that should be a built in feature of every consumer OS.
The same goes for Google Photos. And I imagine that Google photos also doesn't let you edit it a column in the middle of a table. It's trivial to do in real life or in MSpaint or any real image editor but somehow exceeds the limits of mobile apps.
Not to sound harsh, but you come at this with an somewhat old perspective, the same one I grew up with too and probably also retain too much of.
People don't open their phones looking for something like paint or notepad apps, they want a messenger/social network to connect with their family/friends which is most likely why they got the phone in the first place, and if they're "advanced", they'll even edit their own photos and images but via a whole host of various phone image editors. Sometimes the social network offers those things too, sometimes as separate apps, people use that sort of stuff instead of looking for "paint.exe" or tools to crop/edit images in a more, I guess "crude" way that you and I might be used to and favor still today.
For example, the gallery app's image editor on my phone doesn't let me cut out a piece from the middle and then let me pull the sides together. Eg if I have a picture of a table and I want to cut out a certain column. This is super easy to do in paint, but on my phone I need to look for extra (ad-riddled) apps for that.
Also, there's no way that phones are mainly for social networks. It's estimated that there are 5.5-6 billion smartphone users.
I was worried about this when they were younger though. The youngest played a lot of games only on a phone, but even he seems to have moved on from that.
I think it helped Microsoft historically that people used their operating systems at home, although even then a lot of people would have learned Windows at work or school first.