In my game everyone can create their map that's uploaded to Steam Workshop. Its' id is used to create leaderboard. I've recently switched to Steam Leaderboards as I get from their service 10,000 of them without any additional cost. It works fine until I reach the limit or try to port game to other platforms..
I wish PlayFab would have something similar to ChilliConnect where pricing is based on api calls instead of MAU. Current pricing doesn't make sense for low traffic leaderboards. For ex. 200 leaderboards with 100k MAU costs less than 1000 leaderboards and 10k MAU.