It is a full blown Linux OS. You can switch out of the gaming specific mode/UI to a Linux desktop environment using KDE. There you can install your own software and use it like a normal computer.
The only limiting factor is that the root file system is read only by default (can be disabled). If you want to install system level packages, you can work around this by using something like distrobox.
I think most proprietary apps these days have frequent updates because they don’t actual have in house testing and use frequent updates to constantly roll out changes. They are also constantly changing the app with feature switches/AB testing to increase important business metrics.
This same strategy can be seen in the gaming industry with games being in an alpha/beta state for years, at least they are upfront here of the unfinished quality of the software.
None of this would be possible if software was still shipped on physical media. Companies would actually have to test and think through product functionality before releasing it.
Even the non glass icons look terrible, they include some automatic blur being applied.
I actually only played the original Call of Duty and the sequel on PC when they released 🤣