The work guidelines says to use disambiguations when they seem useful, but was added to avoid people adding "Scorpions song" disambiguations to every single Scorpions song and the like (since that data is shown both in normal and inline search), not to heavily restrict disambiguations otherwise.
My general opinion is that disambiguations should be a last-effort thing, and we should just display the data we have better when searching, mostly because disambiguations aren't translatable. At least unless we decide to do like Wikidata and have a different disambiguation field for every language!
That said, until that data is displayed better (like it generally is for works), it does make sense to have disambiguations on anything that has any risk of being confused. I probably still wouldn't add it to an artist called "Fissfhearistofeles" because it seems very unlikely two people would come up with the same nonsense name anyway, but I'd say it's reasonable to add it to anyone with a standard English name, for example.