Umm, there is enough medical and biomechanical data out there that shows it is causation. It is a fact that gloves allow people to hit harder with less chance of injury to the hand, as well as less superficial injuryHe to the head/face being struck. It is a fact that since the gloves were introduced the number of KO's and TKO's from striking has gone up. It is also a fact that the gloves do not actually reduce the incident of TMA/concussions and with the increase of KO's TKOs the incidence of TMA rises in relation to the pre-glove era. A KO is actually a symptom of TMA. There is also supporting data that the incidence of death in modern boxing is higher than the bare knuckle era.
Now should we actually care about these facts? Does it matter, is it better or worse than other sports with hla high incidence of head trauma? That is a different debate entirely, but the data is there. And the consistency of the results, first in boxing and then in MMA gives a much stronger case to the argument of causation than correlation. If we didn't have what amounts to over a century of data as it relates to the impact of gloves, on both the striker and target, maybe you would have a case for correlation over causation.
The argument surrounding the facts however kinda reminds me of the NFL denials years ago but I get why the denials are there. Many found pre-glove MMA boring because of the bias towards grappling and long fights etc. Also, forget about the barbaric reputation of the pre glove time period, bare knuckle boxing is an illegal sport in many places. So from a business perspective doing away with gloves would likely hurt the sport.