I don't really care about ranking (or play the kind of leaderboard stuff that uses it) so I can't comment on implementation. I think it's genuinely hard to do in team competition environments, though.
I know with certainty it's extremely hard to do in heavily team based sports like football and basketball, because that I do pay attention to. Maybe MoBAs are closer to baseball where even though it's a "team" sport, you actually can isolate out parts reliably enough to measure effectively, but I don't play them to know for sure.
I just find any and all rubber banding (an opt in "skill handicap" casual mode is fine; dynamically changing it mid game just makes everything feel like horseshit) a truly nauseating excuse for terrible design.