I mean, there's lots of things in OSes that you don't need but are very useful to have. I love having access to Paint when I use Windows, but it's certainly not a hard OS requirement.
I imagine you're reeling at the idea of an app store on PC primarily because you know the Microsoft store to be absolute dog shit, and you'd be right, because it's a steaming turd. It's full of crap, fraudulent paid copies of open source software, outdated software because the dev hasn't bothered to update the WinStore listing, etc.
If you look over at the Linux world and installing apps is generally as simple as: open the software centre, search for software, press the install button, you're done. Updates will be done either manually or automatically through the software centre, for all of your apps.
Now, contrast that with what people actually do on Windows (because they sure as fuck aren't using the MS store): open your web browser (hey btw we noticed you're not using Edge, do you want to switch???), search for the software, make sure to click the link to the correct website (which isn't always obvious if you don't know the developer name), navigate to the download page, select Windows [version] x86_64, open your downloads folder, run the installer with admin permissions, go through an installer, delete the installer file, delete the shortcut it added to your desktop. Updates will be handled by an updater service for each individual app and most love to start running immediately after booting your machine.
A better app store is absolutely something Microsoft should be looking into