https://musicbrainz.org/doc/Style/Work#Disambiguation_comment says:

Add disambiguation comments only when two (or more) works are similar enough to be confused, not just because they have the same name.

https://musicbrainz.org/doc/Style/Specific_types_of_releases/Soundtrack#Work says to add a disambiguation comment 99% of the time:

The name of the show or film should be placed in the disambiguation comment along with an additional distinguisher if applicable (often the year).... If the song has the same name as the show or film, there is no need to duplicate the title in the disambiguation. 

Which is correct?  If Style/Specific_types_of_releases/Soundtrack#Work is correct, then I think Work#Disambiguation_comment needs to be updated to say that Works that appear on soundtracks override the normal guidance.