It's not like they need any help from Refs. I would have joined your voice but this reminds me of Inter fans back then when they were accusing Juve of getting helps from Refs when in-fact we were too good for them and too good for most of the European top teams.
Mistakes can happen but I doubt Barcelona or even Guardiola thinks of how will the ref perform tonight in the locker-rooms. They're just too good, and I hate to admit it.
Juve was a great team too in the late 90's or 2003 but in 4 CL finals+1 CL semifinal, we ended up with only 1 CL.
Now imagine if we got the little push Barcelona is getting. What was gonna happen if Mijatovic's goal in 1998 was called offside, or Inzaghi's goal at 2:2 in the semis against United in '99 wasn't called offside? Or if our opponents were getting red cards for nothing?
We could have had more than 1 CL, right?
Barcelona are indeed too strong but they're also getting that little push that secured a CL final for them both in 2006 and 2009, as well as a quarter final and maybe even a CL win in the end in 2011.