I don't think I explained it right. First of all, they are two different things. Flower power is an OP form of the game, and is one of the most popular UHC game types, every flower gives a random amount of a random item, it could be crap like say a stack of dirt, or it could be an enchant table, that is the point of the game, although it may sound weird, it really is a very fun UHC game. Slave market is an entirely different thing, every player starts out with let's say 15 iron, they can either keep the iron, and get assigned a random team, OR they can use the iron to bid on other players, who are good at UHC matches.
Sounds fun. But, first there should be a "Normal" Uhc. Maybe after a few months they should add the "Flower power" and the "Slave market". It does sound fun, but if they do that then it would take longer for Uhc to get out. (For players can play)
Badlion is a really close competitor. If they ran fully automatic games, I believe they could be more popular than Hypixel.