Remember Arthur Andersen?
Sure, I am not saying the Messis' should not have had better people handle their taxes, I am just arguing against the merit of Messi's conviction. Basically if I get screwed over by one person, no matter how trustworthy and professional that person has been, I will be convicted? I'd better study tax codes myself to do my own taxes.
If it was Donald Trump being convicted would you care to defend him? I have no sympathy for rich people that don't want to pay their taxes.