Uhm, no? Because for some reason the defense was just lacking, and without Boateng it is even flimsier. Mexico isn't a side to take easy and Sweden just as much isn't. South Korea honestly got really lucky to play a German side with an already relatively bad defense compared to 2016 (and Neuer lacking match-rhythm), even made more apparent with Boateng being absent - and to score that first out of VAR moment. I honestly doubt that Germany would've been sent home if Boateng didn't get that second yellow during the Sweden match, but to be frank: he should've gotten a direct red card earlier in that match, so they probably would've lost that match as well - so nothing would've changed at the end of the day.
Sure, if you look back interviews about the socalled golden generation of England (Lampard, Gerard, Beckham, Scoles, Ferdinand, Rooney), they'll also said that there was a bit of a weird vibe during their moments on the England team, because they were too embroiled in their club-rivalries, and forming clicks during breakfasts and such - but when it comes down to it, they also said that probably the biggest complaint they had was that they weren't used correctly on the pitch. Which brings me to Spain of 2008/2010/2012: Basically half of the team was from Barcelona, the other half Real Madrid. Had no issues to play with each other, even when you have guys like Pique and Ramos right next to each other (with Ramos taking offense to Pique using the Catalonian flag). Because they obviously used the right system.
So to use internal dislikes as a reason why a team has failed is just weird. Like you just said: They're pro's and there's often enough a more structural reason why the team has failed. Players not being set onto the right position, players lacking rhythm/fitness, fear of losing, expectation set to high, underestimating the opponents. Look at the Netherlands during 2012, sent home in the group stage after playing the final in 2010. Look at Argentina this year: The players LOVE playing for Argentina, but the system just doesn't work (and Sampaoli lacks managing skills).