That and four bucks will get you a cup of coffee. Talent is what drives this league. MJ himself is the biggest contra-indicator for your argument, Kobe/Shaq weren't much better, and LeBron is no paragon of cohesiveness himself. Camraderie is nice, and is certainly better than its lack, but I hardly view it as necessary to be a good team.
I don't think you can extrapolate what Simmons has done in Philly to what he would do in SA. You act as if such playoff "shrinkage" is 100% inevitable and will never change, but I disagree: plenty of players have been viewed as playoff chokers until they aren't. This quote also carries the implicit assumption that the first round is the ceiling for the Spurs-with-Simmons. I disagree, again depending on what the Spurs have to give up.
I would trade the Spurs' current situation for that of one of these teams in an instant. Simmons doesn't necessarily get them there, but he would be a large step towards it. Talent trumps all, and Simmons has plenty of it.
See above re: extrapolation. And what Doc Rivers said was an opinion, not a fact, so it can't be classified as true or false. Damon Stoudamire said no team with Avery Johnson as the PG would ever win a championship, and it happened that very season.
I don't want Simmons to flip him for true star later. I want him to pair with said star to make a le push.
I especially disagree with your last sentence. I don't think the Spurs trading for a #1 option, or signing one as a free agent, is impossible at all. I'll give you unlikely, but not impossible.
As you said, Philly was a lucky bounce away from having a great shot at the le in 2019. That doesn't speak against them at all. Not succeeding doesn't mean that success was impossible, or that it would be impossible in the future.
Philly, in terms of fanbase and ownership, is basically a show. They wildly overpaid Tobias Harris and can't (or at least won't) keep their drama in-house. I absolutely think the Spurs can do better, at least in terms of being smart about handing out contracts and managing the media.
Simmons is under contract for 4 more years anyway. I'm not worried at all about him leaving in free agency because there are far too many things that can happen between now and 2025 that will make a much bigger impact.
The "no Simmons at any cost" camp is hard for me to understand. Of course it isn't hard for you, because you're in it.
We come to different conclusions because we make different assumptions. It looks like you think Simmons will always choke in the playoffs and will never be worth his salary. I think he has enough talent that, while not being capable of carrying a team to a le like a true superstar, can still be a solid #2/#3 guy on a contender. I don't think a wall of text on the part of either of us will convince the other at this point, though.