Agreed to a certain point. If you have a rapper’s album, often they won’t credit anything for the vocal performance, because it’s to be assumed it’s him. In that case, it seems quite reasonable to just add him to any tracks (especially since it’s pretty easy to listen to them and check that yes, that’s indeed his voice there). If you already have a credit (like “produced and written by X”), I’m not sure it’s a good idea to enter more than that, especially when that “produced” seems intended to cover the whole “did stuff in Ableton or whatever” concept already.