The immortals teams that can beat susanoo and others highly p2w teams are teams with ninja like tsunade hokage or six tails naruto.
Sure they are maybe a little easier to get than the susanoo brothers but they are still p2w ninjas very hard to get so it's not like everyone can suddenly beat the * of opponents way stronger. Lightning blitz and water blitz are way more easy to build cancer teams in my opinion. No wonder why they are everywhere.
Space time is not a good representation of what teams are the most used by the community since it is just the whales fighting each other.
As for your statement that everyone hate fights that last 10 rounds well that is just your opinion. It's like in every other MMO there are different style of gameplay and everyone doesn't like the same thing. DPS, Tank, Healer, Crowd Control, AeO, etc.
For example i really don't like the gameplay of lightning blitz. I think it's boring and require no skills at all so i never jumped on the lightning blitz bandwagon.
In my opinion those 10 rounds match were way more interesting than a match over round 1 or round 2 wich is just one sided slaughter while in 10 rounds some interesting plays can be made and a player can turn the situation around, making a comeback, etc but that is just my opinion.
Immortal teams will die at some point. No one use them in china as far as i know so i guess it will not be enough to have 3 heals against the end game meta now i can't say for sure when it will end.
As fore fights that last 10 rounds all the chinese space time fights that i have seen where a lot worse than here in that regard.
Everyone had the same team with earth main, roshi, naruto kurama, hashirama sennin/killer bee and the fights lasted 10 rounds with maybe one ninja dead at the end max so you tell me if it is better.