It is a balance between playability and automation. Even minesweeper does that (auto deduce that a large region can be opened up). What I described is only the first-order "convenience" checking to avoid the pain of going way back because of a miscounting.
Regarding the hint button. I don't want to use it precisely because I don't want to "win" by repeatedly getting hints.
If you start adding any automated processing like that, then you're only a couple more processes away from the game just solving itself without you.
The elegance of this implementation is that you are doing all the solving. Unless you specifically ask for help from the hint button.