I see what you are saying but the statistics also speak for themselves. You could also take the squad from 2013 as an example when Bayern played a record Bundesliga season with 98:18 goals scored and won the Champions League and there was almost not a single game where Bayern made mistakes. It was absolutely superb and therefore it doesn't make sense to now talk about the strongest squad ever. In the end success is what counts. I am not someone who disregards performance when there are no trophies, that can happen. Sané is a good example. Everyone says he is one of the best in the world. Perhaps in 20% of the games he plays, does that make a player one of the best in the world? Would Guardiola let one of the best players in the world easily go?
We'll see how they are going to do next season. If it is the same as this season, it would be a good proof that this squad is certainly not the best. I already doubt it but maybe some have their reasons to believe that.
I think it is not about being able to say he is one of the best or not, he is definitely a great player and I wouldn't know if he is the best right now but he is definitely great but also being able to win something. Imagine if Messi was still Messi but Barcelona never won a title and never won any cups etc etc, wouldn't messi be still messi?
But the team around a player matters, every player who has been great in their career had some good teammates, even if not for the team they started, they would leave for a team that has those great players, which is why it makes so much sense for major stars to leave for big teams. This means that Sane is great when everyone else is great, and he is not great when the team doesn't do great. Like he played awesome at UCL and yet they still lost, that's a great example.
The comparison is not appropriate. Messi turned Barcelona into a team that Barcelona has never been before. There is only a couple of players that can improve a team that is already strong and that only works when they deliver their best performances game after game.
I absolutely agree with you that the team is the most important of it all. But what is the possibility that Messi would have played for a club that never wins a title with him? The difference between good players and those who are the highest world class possible is consistency. Like Messi, Ronaldo, Mbappe, now Haaland. Sané doesn't help a lot when he is good only a few games per season.
There are statistics how many games Messi decided with the first goal of the game or with a goal that won Barcelona the game. He is the best of the best in that statistic. I will try to find it. Sané is nowhere to be found except for the year where he became player of the month in the Premier League two times I think. And yet Guardiola didn't even care that he wants to leave. It has a reason.