You mean the era of Messi? Messi has made Barcelona into what they are today, that along with support of Spain’s golden generation of 2008-2012.
When Barcelona lose Messi and they struggle to replace one of the top 3 all-time greats and they have 6 years in the wilderness, I’m talking surpassed by Atletico, maybe Valencia and well behind Real Madrid (would never happen because La Liga isn’t as competitive as the Premier League and Barcelona and Madrid will still control all the leagues money) will they still be regarded as one of the biggest clubs in the world? The answer is no.
Manchester United still are, that shows just how big they was and still are and let me tell you losing Sir Alex is a lot worse than when Barcelona will lose Messi, United losing Sir Alex was like the heart was ripped out of the club and the club had to have a heart transplant, when Barcelona lose Messi it will be like losing a limb but recoverable in 2 or 3 seasons.
Manchester United prides itself on Europe’s capital of trophies, so not sure why you are going on about trophies, they are the most successful club in the English football (the most watched league in world football), European trophies play 2nd priority in England to the Premier League and clubs from 2nd rate leagues like France/Holland and even Germany cannot be regarded as bigger than the big clubs from England/Spain and Italy because interest in these leagues is just not there, when people watch MMA they want to watch the best (UFC) no one gives a shit about Cage Rage, same with football.
As said previously, the Manchester United crest is the most recognised crest in world football, people know the Manchester United badge who don’t even like football, can the same be said for Barcelona? United claim to have the most supporters in world football (1.1 billion worldwide), can still attract the biggest sponsorship deals/pay the highest wages/highest fees and said the most successful club in the most watched league in world football.
Real Madrid and Manchester United are in a league of their own in terms of size, that is just a fact.