The way I see it Bruce was not a founding member of that group, he joined 4 years after they formed and what 9 or 10 albums in, and dozens of hit singles later? So he really had no ground to give any sort of authority. I’m sure the others valued his input and music but he did not contribute a lot to the band, not his fault but more the fact they had Brian, Mike, Carl and Dennis doing a lot of the work.
You're not wrong -- actually your figure of "9 or 10 albums in" is exactly right, depending on whether you count Concert.
He can be first heard on the 16th "hit" Beach Boys side, if you define "hit" as a top 40 song. Technically their 12th top 40 single. ("California Girls.")
I think you're right that it was inevitable that a clash was coming as Bruce became more prominent on the albums, starting with 20/20. Particularly on Surf's Up when he was carrying a lot of the arranging weight that Brian had abdicated, and given that there was really no-one else in the band who was able to do that, no-one should be surprised that he got a little big for his britches and that a blow-up took place. Things were a bit more balanced on Sunflower because Brian and Dennis were more involved, although again Bruce was the only really capable arranger in the band aside from Brian at this point.