Barcelona have been looking for Messi a lot on the field this year. When big stars fall, they create big gaps. They couldn't make up for Messi's absence. If they don't create a big star, they will lose the league to Real Madrid again. Real Madrid have the advantage of dominating the league more than ever. They seize this opportunity well. The Spanish league will be similar to the German league.
You could say the same thing about Real Madrid as you did about Barcelona... They lost Cristiano Ronaldo but didn't play worse and won La Liga again... Maybe it's the coach, not the missing star... Barcelona still have good players.... By the way Messi also didn't play very well at PSG this year it seemed to me...