Or are you perhaps thinking of ´ (Unicode code point 0000B4, ACUTE ACCENT)? Yes, that one is ugly and should not be used as either an apostrophe or a right quote.
However, making every “skewed” apostrophe “straight” is very easy for a computer to do (e.g. MusicBrainz Picard ships with a setting for this). This is why the MB guidelines say to prefer correct typographical apostrophes.
Note that they are preferred and not required, so you can still enter straight ones, but another editor may update them. I honestly don’t see the problem, but I am very pedantic about other things so I guess I can imagine how seeing the curlies could rub you the wrong way!
"acapella" would technically be considered a spelling error, which is something that we correct.
This article does a good job explaining what artist intent means: https://musicbrainz.org/doc/Style/Principle/Error_correction...
https://musicbrainz.org/doc/Style/Principle
https://musicbrainz.org/doc/Style