I'm agreeing that they DO have a huge wage bill but are careful with the way facts are presented ie. We don't know how many players it includes which would effect the average. The average is the base salary so not including bonuses and other payments, which would make the actual figure higher...
As I understand it, it's because PL clubs vote on each rule change, and in this case - bizarrely - some chose to vote so as not to close this loophole (presumably because they fancied exploiting it themselves)...
They only paid because Chelsea bought João Felix off them, who they'd be trying to shift off their books for a while (and who Chelsea had passed up on just one year ago 🙄).