Having a single example of a good short player doesn't mean size doesn't matter. There may be a positive correlation between size and "skill", and Messi is one of the best despite his size disadvantage.
Germany: Philipp Lahm 5'7" and Mario Gotze 5'9" Belgium: Eden Hazard 5'8" Italy: Andrea Pirlo 5'9.5" Netherlands: Wesley Sneijder 5'7" Spain: Xavi and Iniesta 5'7"
historically the best players have been on the shorter side. Maradona was 5'5'', Pele 5'8''. One of the greatest parts of soccer is that it doesn't immediately disqualify 70%+ of the potential talent pool based on the importance of a single attribute, like height in basketball.
size does matter. You're not going to be a great soccer player if you're 7'4".
It's not correct to disqualify a statement mentioning an exceptional cases - 7'4" is such.
Within limits of regular height, football does not disqualify anybody.
why not? I'm 7'4" and it would be foolish for me to believe that I can become a great soccer player. I'm not trying to be "correct" whatever that means. I'm just saying your size matters. Your coordination and motivation matters too.