I think that what you said is very near the crux of this matter.
As somebody may remember, I am a big fan of Mike's (and of all the Beach Boys) and am annoyed by "Mike bashing". That does not make me a Mike apologist who thinks that he can never do anything wrong.
I think that the "pushback" from the "other Beach Boys", and probably particularly by Mike, WAS one of the reasons Brian ended scrapping SMiLE.
And... know what? I don't think Mike or any other Boy should be ashamed of that. Questioning some of Brian's artistic choices was well among their rights.
In fact, Brian was right and should have perseverated and completed SMiLE anyway, but sadly he was not in a mental state to do that. But this is not a murder case: nobody murdered anything. Searching for explanations of what happened is NOT the same as searching for one or more "murderers".
And that's the problem with a sizable section of the Beach Boys fandom, historians etc.: they are so keen on acquitting Mike, and any band member EXCEPT Brian, from that bogus accuse of "murdering" SMiLE, that they go to the deep end and PILE every and all responsabilities on Brian, Van Dyke and SMiLE itself.
And they end saying far worse than Mike, or anybody at the moment, probably said: i.e., the SMiLE project was deeply flawed anyway, Brian was deeply flawed himself (and in any case out of touch with the "public") and as for Van Dyke... just a self-important wannabe.
In a nutshell: there is something deeply flawed in this matter. But it's not Brian, nor Van Dyke, nor SMiLE, and no... not Mike either, nor any other Beach Boy.
Ive just been using the board's search function to go back on some SMiLE related conversations as a final pass-thru and felt the need to weigh in on this.
I started as a one-dimensional "Mike killed SMiLE, he's the uncultured jerk who ruined a masterpiece" type of fan after first getting invested in this topic. Then talking to some of the other fans here, listening to the arguments in favor of Mike's skepticism and jadedness (including stolen song credits) made me soften my opinion. Not nearly enough for some of the "Kokomoist" faction, but much more than the staunchest "Brianistas."
I've since gotten reinvested in this subject after a long hiatus, compelled to comb over every reputable source and finally put the matter to bed. I went into this endeavor with my more "nuanced" take of Mike. And for the record, I still think it's a bit fishy that no one can cite specific anecdotes they remember about nasty things Mike supposedly said. (Priore claims Mike commandeered Derek Taylor's efforts and through him announced the cancellation but I don't buy it without a corroborating source. Priore also claims Mike staged a fight for the cameras when Oppenheim was filming for
Inside Pop, but this has been disproven. He lies or intentionally misleads elsewhere in the book too.)
Despite my willingness, even bias, to give Mike as much BOTD as possible, he's always the most frequently cited factor for why it all came apart. Whether you want to say Mike was "just" the straw that broke the camel's back against all the other factors, or some kind of malevolent unyielding force who schemed behind the scenes to throw wrenches wherever possible, he's always the #1 and sometimes only factor cited. Not just by Brian and VDP, but practically everyone except the Beach Boys themselves (who blame drugs primarily--certainly a legit factor). It's actually kind of insane how united the primary accounts are on this, despite never elaborating with in-depth stories of what he actually did.
In short, no one can deny Mike was a significant contributing factor in SMiLE's demise who is arguing in good faith. The real question is if he was the #1 factor or lower on the list, and even then I think, looking back, his "disgust" (actual quote, cited twice in the wiki by different sources) hurt Brian more than anything else. That's the real wound in Brian's soul, the muzzle on his muse--why he was afraid to go "too far" again after that and reigned himself in. I think some elements of the fandom want to live in a fantasy where there was never any drama within the core group, everything happened for the best and everyone was happy with how it all turned out, no regrets or grudges along the way. That, and they lean towards Mike's political bent, not just current but since the '80s when the band aligned themselves to Reagan and set their "all-American good boy" image against the psychedelic stoner counterculture which SMiLE represents. (Priore was absolutely correct in his assessment of the band's public disdain for SMiLE until at least the GV boxset if not after. Even with BWPS, did ANY of them ever reach out to congratulate Brian on that or express admiration for the finished work? If so, it's hardly talked about.)