Yeah, after a few more trials, summon breaker is only effective against bad, baaaaaaaaaad players that don't read the cards, as summon breaker only applies during the main phase 1.
They can skip it, and spam as usual in main 2.
It does allow yamato to stay one more turn usually, but mineswell play threatning roar, that is chainable (although summon breaker is every turn).
But there is still summon limit that did actually work way better than summon breaker. So if you want to try my "awesome" idea, it does work, but not with summon breaker, only with summon limit.