A file has a dialect: how densely it comments, how it names things, which of several correct constructions it reaches for. That dialect is not decoration. It is what lets someone skim the file and find the part they need, and a patch written in a different one costs every subsequent reader the switch.
The cost compounds in a way a single diff hides. Two dialects in one file leave the next contributor with a question the file no longer answers — which one is this project’s? — and the usual resolution is a third. What began as a stylistic preference becomes a file nobody can skim.
So the local convention wins over the better convention, absent a reason to change it. Where the surrounding style really is wrong, that is a change worth making deliberately and saying out loud, across the file rather than in the one function being touched. Silently correcting it in a patch about something else produces the mixed file rather than the improved one.