Only because there have been so many of these battles over the years.
However, in the beginning, when the Thing had not met the Hulk, all Marvel readers were BEGGING for a confrontation between these two.
Back then the strongest Marvel heroes were few and far between, being The Thing, The Hulk, Thor & the Sub-mariner. That was the top four. Period.
So Marvel fans have always speculated on who would win in a battle if they fought. That is why all the books featuring these early battles are so expensive also.
FF #12, FF #25, & 26 and JIM #112. Later on Marvel introduced many super-strong powerful heroes and villains, but in the early days it was only these four.
I think this is one of those "you had to be there" moments to fully appreciate these stories as we did in 1962-65.
By the way, the battle between the Hulk & Thing in FF25 & 26 tops FF #12 in my opinion.