You're confusing two arguments here.
The Argentina squad has been better quality wise than Portugal. That's my argument. Maybe Euro 2021 will be the first time where I'd say, individually, the Portugal squad is better than Argentina's.
The fact that Argentina have underperformed, although they've had class individuals is a separate argument. That comes down to luck, coaching, form etc.
So, for me, any Messi fans or otherwise who think that Portugal has had better squads (not counting Euro 2021) is wide of the mark.