All of his setups are based off of the fear of big OH damage, or his deep stun off of 3P (which launches when double tapped).
+9 allows him to manifest that threat with impunity.
If they countered immediately, that actually wouldn't change the situation much as Bayman is one of the few characters not going to be relying on too many strikes for big damage.
I can frankly just spam offensive holds if they got counter happy. But you have to understand If they did nothing, they would fall straight into my biggest OH. If they slow escaped, they would fall right into my OH's anyway since they'd be blocking coming out of it. If they waited and striked, I would not only land my OH, I would get high-counter damage for it. If they were mashing buttons while slow escaping, the OH would still win 90% of the time as anything they tried would be inaccurate as a mother fucker thanks to crazy input and the sketchy buffer system.
And if, on that rare occasion, they decided it would be more fun to throw me out of my OH, I can mix it back up with my kick to put the frame advantage right back on. This kick can also result in a wall hit leading into other mixup possibilities (remember I still get ground throws if i let them crumple to the floor after they hit a wall).
All in all, it's a platform for giving people a great fucking headache.
And no its not perfect, because nothing in DOA 4/D is. But it is better than pretty much anyone elses offensive options since it covers so much. Even Helena's bukuho loop required mixing up with unsafe options. . . I have no such problem here.
Considering Bayman can go straight into this platform of death from a high jab string makes it only more OP.