Its also a bit of a circular argument. Could it be that everyone in Jack's era was elevated due to shallower pools? People always cite the other HOF's Jack played against, but its possible they were able to have such success given the relative lack of deep player pool.
The pro-tiger side will say, "Jack only had to beat 50 or 60 other guys (whatever it was), few to no international players, country club pros", etc. And then the pro-Jack side will say, yeah but Jack was beating all time greats. Palmer, Watson, Player, Trevino etc. Palmer had 6 majors, Watson 8 etc And then it goes in circles.
Jack facing multiple HOFers doesn't refute the shallow player pool argument, In fact it probably re-enforces it. I wasn't alive when they were playing so I cant comment myself. But it makes sense that its a lot easier to only have to beat 50 guys than 100 to win a tournament, And if that's the case, then that played a part in Jack getting to 18, but also Watson getting 8. Watson having 8 majors does nothing to refute the initial claim that Jack faced shallower competition.
Similarly, the anti-Tiger guys will say, "Tiger never beat anyone, few multiple major winners" etc. But you could easily argue that's specifically because of Tiger. Its because of Tiger's dominance that there were so few other multiple winners. This argument doesn't necessarily offer evidence that Tiger didn't face any true competition.
So in summation, the pro-Tiger argument seems to be stronger and more logical, whereas the pro-Jack/ anti-Tiger is really a circular argument that is tough to substantiate.