If he would play for Palermo 4-5 seasons In that case he would play for the team which doesn't play at the highest level, this means that we couldn't know how he would play at that highest level for top aims, top teams and also against top teams of europe, he may fail to play on that level. How can we consider him as world class when he've never played at the world class level of europe.
No you don't understand what I'm saying, maradona was playing for a team which was top team in Italy and was playing in europe for a top places. Napoli was world class team those days. so he was world class

I'm not saying that player who once played for the poor team can never be the world class. He wasn't world class in Padova but he became such in Juve. Is it clear now??
and finally people, who can't understand this simple logic, haven't you tried to think while reading

try it's not difficult