That "Messi carries Barca" bullshit argument didn't age too well.
As soon as the Xavis, the Iniestas, The Puyols, the Alves', The Etoo's, The Villas, all the greats that made Barca unplayable at their best were gone, Messi has been collecting humiliation after humiliation in CL.
Messi was just 1 incredible player in an incredible team, be it Pep's Barca, or MSN Barca.
It's a mixture of things but you're only pointing out the things that enhance your overall argument. Of course Messi was elevated to higher heights and won more due to the generational talents around him. Unfortunately they were mostly replaced by average footballers.
Alves - Roberto and Semedo. Roberto is an ok squad player, Semedo now plays for wolves..
Midfield since Xavi left - Paulinho, Arthur, Vidal, Frenkie brought in. Vidal had pedigree but was already on the decline + a strange fit for our team. Frenkie has shown half of what we all thought he was capable of. Paulinho and Arthur are two average footballers.
Eto'o - replaced by Suarez which was great, absolutely no quality back up signed though. And of course he won something with him.
Puyol - Mascherano did well to fill his boots 14/15 season. Since then... Umtiti (need I say more), Lenglet (decent but not elite).
The 2018/2019 season Messi carried us in the UCL and league. It's unfair to say otherwise. Last season not so much even though his stats were great, it was more an overall team decline. BBZ too, you've said how Messi being great in valverde years was just masking over a declining squad and the only reason we had a chance to win anything.