Pretty sure he was not talking about befriending them. He's talking about if you're having trouble finding a 100% eidolon to use as a support, simply run a low cost AP stage to refresh/change it until one appears. The eidolons may be hard to get but they're not hard to find as a support, even if not on your own friend list. Whether they're on your friend list doesn't matter, it can just speed things up a little.