Why? I can see everyone turn hybrid soon
That's not a big act ender tho.
Just think about it, the first two acts ended on big moments of the story changing from one big plotline / area to the next.
The first act finished all the introduction to Wano and the villains, including Kaido. Ending with Luffy being defeated and being throwed in jail, while the rest of the crew finds out about it.
The second act finished all the raid preparation, training and power ups setup for the monster trio, and also giving a bunch of motivation for the alliance. It finished with the whole confrontation of the capital, Yasuie's death and the end of the preparation, going right into the night of the raid.
I feel like for this third act to end we would need either a big death, a big reveal or Onigashima finally getting above the flower capital, either falling on it or just getting there at least.
Just showing the end of the match ups and their hybrid forms doesn't really change the plotline and dynamic of the current act.