He's established as a rival to Baki, guns for his woman, and goes on a journey to defeat mainstays like Doppo and Shibukawa.
And then he runs into a brick wall named Jack Hanma, and suffers from what can best be discribed as targeted harassment from everyone who decides to vent on him while he's in banadges. Including his own father, as he's hobbling on crutches and in a body cast.
Yeah, fight anyone, any time, but this was excessive. Doppo never went gunning for Shibukawa after his loss, the same way he gunned for Ali. He didn't go to his hospital bed after his beat down by Jack at the Maximum tournament, and declare it a win.
And Shibukawa wasn't exactly in a hurry to avenge his loss to Jack, either. In fact, he hasn't challenged him since.
There has to be more to the story. Maybe the writer got fan backlash, and changed his plans by making his pet character into a punching bag?
Doppo and Shibukawa were just sore of the way they went down to a sportsman, as Ali Jr. is used to be protected by the rules and they don't see themselves as that kind of fighter. Taking proud in their brand of fighting, trying to save face, they went and bullied Ali like the sore losers they were. But they ultimately respected his strength and considered that they started to impart a lesson to him, so in their hypocritic mindset they felt justified.