But ZZ is equivalent to :wq, which is different. If OP finds themself in a text file in vim by accident and started typing a word, they will likely NOT want to save those changes. (Hence OP's :q!, rather than :q.)
Oh, cool! I didn't know about view, actually... I'd been using vim to poke around in files because I'm familiar with the navigation key commands, and was always keen to make sure not to edit something. But opening as read-only is great!
But ZZ is equivalent to :wq, which is different. If OP finds themself in a text file in vim by accident and started typing a word, they will likely NOT want to save those changes. (Hence OP's :q!, rather than :q.)