since ronaldo joined real madrid in 2009, messi still scored more la liga goals than him
Messi played more games.
how old was Ronaldo when he arrived at La Liga? That's the relevant fact if you want to compare the two.Messi played more games.
He scored more goals per game.
So Messi scored more goals per game like it is said in the post you quoted.
When they retire no one will look at “from when he started” Etc.. it will be overall career goals/games which Messi is well ahead in ratio.