>>53493801>Type specialist gets 1 out-of-type mon that gives them some weakness coveringThat misses the point of monotype team building, which is that you have to work around your weaknesses as best as you can within the constraints of that one type.
Gen 9 turns this on its head a bit with tera types, but at least you always know that the off-brand Pokemon is going to have the type associated with the trainer.