I think it boils down to the standard of the club. Many football fans will not admit it but Barcelona is among the top 3 biggest clubs in the world. When a club as big as Barcelona has a little failure, it would be viewed as a very huge one meanwhile this is what other teams get a pass for.
Let's put what I mean practically. If you ask any football fan to choose which club has been more successful in the past 10 years between Liverpool and Barcelona, most of them will say it's Liverpool, but are they?
Liverpool has the Champions League in the last 10 years, and Barcelona also has won 1 Champions League in the past 10 years.
In total, Barcelona has won 16 trophies since 2015 while Liverpool has won 7 but because of the standards of Barcelona, this is considered poor. It's the price for greatness, I understand.
I like the way you analyze the whole issues in your comments but I will also like to know the other two clubs alongside Barcelona as the biggest clubs and the basis in which you rate them. Moreover, I don't think any sane and experienced football fan would rate Liverpool ahead of Barcelona despite the recent challenges they are experiencing. Actually, Barcelona performance has depreciate but not to the extent people are assuming it. As you pointed out earlier in your comments is exactly what I noticed too. The reason their poor performance is noticed and being talked about is because of their standard and of course, expectation from them is beyond imagination. Considering the squads that made up the current Barcelona team, one can not expect too much from them as everyone is doing right now. These boys are too young to be mounted with much pressure to play extraordinarily.