You can have all that knowledge behind you but in that moment on the pitch when everything is going to shit nothing about the past matters, it's all about the present and players panicking and resorting to hoofball need one person to just say 'slow it down, calm down, start passing' and then lead by example and people will follow. We're mostly sheep at the end of the day looking for a shepherd. I know that through playing football myself and seeing the difference between players panicking and hoofballing to suddenly playing tiki-taka because they're taking a second to think about what they're doing after someone has told them.
Every time the camera focused on Messi during that Roma game it looked like he was doing nothing at all. It's similar to when everyone said Mascherano was the leader during the 2014 World Cup even though Messi got all the plaudits. Sometimes that warrior spirit is needed so that people can feel safe and secure knowing in that moment somebody is standing up proud and not just standing there looking dejected and sheepish. That visual and audible message coming from a leader can be enough to make everyone snap out of the panic and start doing things properly again.
You don't get it and that's fair enough but I've seen the evidence of it. Different times call for different leadership approaches and for many a time all it requires is for Messi to do his usual run past four/five challenges and either score or play an inch perfect pass and boom, goal and that's fine but those times come against easier opponents. When somebody actually puts pressure on you and you're seriously under the cosh, you need someone loud and proud to stand up and take the game by the scruff of the neck and everyone rallies behind them. Annoyingly Steven Gerrard was excellent at that and he's remembered the way he is because of that.
There are many, many occasions in the face of extreme pressure that Messi has wilted. Sometimes I agree that there isn't much he can do if his team mates have just lost it or they're not good enough but he so often looks like he can't be arsed in those moments and they leave a lasting impression just as much as his incredible goals, assists and dribbles do. Much like Ronaldo having a hissy fit is part and parcel of him when things go wrong, Messi turns into a shy little child.
Nobody is perfect and that is Messi's big flaw in amongst all of his amazing attributes.
Well, if you're prone to ignore that he's done all that throughout his career then sure, he lacks that.
But if you're actually fair to him, he's done it in a lot of games vs Real Madrid, Arsenal, Chelsea, Milan, Bayern, Atletico, Manchester or even finals vs 2nd fiddle teams (Sevilla or Athletic) when they tried to wipe him out of the game with fouls or Barcelona were inoperant. Nevermind the bunch of players that have tried to do the same on a weekly basis in la liga, which often end up ridiculised (special props to Espanyol here).
You're basically criticising him for not grabbing the bull by the horns in the Roma game here, no player has stepped into the pitch on every important match of his career and delivered a top performance of football and leadership, if you watch the game again (because I did, 3 times in the same week, and recorded clips that sadly I lost) you can see Messi dropping deep (as deep as to defend with the Right Back in two occassions) and try to start plays from a "5" position, things he couldn't do because our midfield sucks, we lacked mobility and he had a bunch of Roma player on him.
If you think that our players would feel more confident in watching a guy that carries a hierarchy every time he steps onto the pitch with him, a halo of him being untouchable for his teammates, losing his cool and start yelling like he's Roy Keane then that's your opinion, if I have the best player in the world in my team, he's famous for not losing his cool and suddenly I see him rattled, chances are I might become even more anxious.