So hindsight is 20/20 right, there wasn't any horrendous points where it was clear this fight should be stopped. Everyone is watching this knowing what happened and screaming about the ref and the corner. Well, it didn't appear at any point leading up to the KO that he was completely done, it looked like a boxer out of his depth who had been stunned and hurt. The only moment where I say it probably could have been stopped is when he shot for a takedown at the end of the first, but even then I don't know if I'd be saying that without knowing the eventual outcome.
Obviously this is horrible and sad, but attacking his opponent for celebrating is plain wrong. Should the ref have stopped it, yes probably, should have seen that it wasn't going to get any better and stopped it, but at a small boxing show like this refs generally allow fights to go longer than they should because often times fighters are outmatched. As far as a 1-2 fighter fighting an undefeated fighter, it's commonplace in boxing, you don't get noticed until you're 14-0 with 14 knockouts, so guys get fed fighters tailor made for them all the time.
As far as the corner goes, they probably should have throw in the towel as soon as he was knocked down again in the second, but we don't know what he was like between rounds or if he was telling them not to stop it. I am critical of corners quite a bit for not protecting fighters from themselves but the reality is those guys in the corner could be his students or employees, often times guys run their own gyms don't have someone who coaches them, it's just guys from the school who aren't going to go against the fighter. I'm sure the corner feels horrible enough, they don't need people telling them what they should have done.
Finally, I'd say this is more a symptom of the fight game then it is this particular fight. The manw as 1-2 in boxing, fighting in boxing after being KOd twice last year in mma. It's obvious he needed money and was going to go in and take a beating to make some, I've seen it happen a lot. Whether it was standing 8 counts or his previous KOs or a freak accident or whatever ultimately is to blame, I think this falls on the atmosphere of the fight world more than anything particular to this fight.
Side note, did anyone notice the knock down a little after 2 minutes started due to a headbutt?
2nd side note: I'd be willing to bet the majority of the damage form this KO came from his head whipping into the mat after he was KOd. The vast majority of times something like this happens in a streetfight it's because the whip from going down and hitting your head on the ground is far more severe than any punch. None of the knock downs early were super significant, the last punch was hard, but even then we've seen plenty of guys hit much harder. I've felt like something needs to be done about that factor, all the worst reactions to KOs we've seen are from the guy smashing his head on the mat after the KO(think Uriah Hall spin kicking that guy on TUF) but there really isn't anything that can be done.