> - when I see that browser does not allow playing video in the background (youtube on mobile phones)
The browser supports it just fine. Youtube itself disables that functionality (to try to push you to Youtube Premium). You can install an addon from the recommended addons to fix that.
> - when my browser disallows me blocking certain things
The only thing I remember Firefox blocking from meddling with is pages like mozilla.org and their addon store. Which, for security reasons, makes a lot of sense.
> - when my browser prevents me from taking screenshot of things I can see on it
That's a setting, though, isn't it? Unless you mean the optional DRM support Firefox has. You can disable that permanently if you don't like it, though you won't be able to visit many DRM-based websites. I've configured my browser to request permission before playing DRM based content and you'll be surprised how often the permission prompt pops up on websites that host normal (non-TV) media.
Have you tried to watch YouTube in Chrome on android? It will turn off once switched to a other app or tab and it can be prevented. Prevented only on Firefox (with add-on). While other web pages like sound cloud will still play in background.
The only reason YouTube premium's background playing is possible as an additional feature are the limitations imposed by the Google company on the android and Chrome themselves. In other words Google built up the "open source" environment to make this exactly possible. They limited us from our phones and now they are selling features that never have been features - they were normal behaviour
The browser supports it just fine. Youtube itself disables that functionality (to try to push you to Youtube Premium). You can install an addon from the recommended addons to fix that.
> - when my browser disallows me blocking certain things
The only thing I remember Firefox blocking from meddling with is pages like mozilla.org and their addon store. Which, for security reasons, makes a lot of sense.
> - when my browser prevents me from taking screenshot of things I can see on it
That's a setting, though, isn't it? Unless you mean the optional DRM support Firefox has. You can disable that permanently if you don't like it, though you won't be able to visit many DRM-based websites. I've configured my browser to request permission before playing DRM based content and you'll be surprised how often the permission prompt pops up on websites that host normal (non-TV) media.