The only player who achieved more than Yamal at the age of 18 is Pele.
Even Messi at that age hasn't achieved as much.
That's not because he is THAT GOOD but because football has changed.
In Messi's teen years, 433 was just emerging.
90% of teams played 442 with older, experienced strikers.
Football was slower, AC Milan was rulling the world with 35 year old defenders and midfielders.
Only in 2008' Pep introduced a faster 433 with triangles and high pressing.
With an introduction of high pressing, football moved from 33 year old strikers towards teens and players in their 20s.
Further, in 433, the biggest importance is on Lw and Rw positions who need pace, need to dribble, create, score and press.
And lately, all top teams started to play Lws and Rws aged 17-22.
Not because of Yamal but because tactics and requirements have changed.
In short: Yamal doesn't play more than Messi aged 18 because he is better but because modern football shifted towards very, very young Lws, Rws and Ams.
Also, don't expect these new kids to play till the age of 35 or 38.
They will have more injuries due to playing from the age of 16.
They will have a burnout earlier.
And they won't develop mentally.
When Messi was 18, he was slowely being introduced into a team as a sub by Rijkaard instead of Guily.
Cr7 at the same age was getting last 20-25 minutes per match and Alex Ferguson was constantly yelling at him and commenting: "you can't give too much playing time to these kids in order to develop them mentally."
On the other hand, today we have Lws who are superstars and starters from the age of 16.
He will be mentally finished sooner than Neymar and Adriano.