I disagree, clubs and agents help each other out all the time. While obviously other clubs wouldn't give them the money they wanted, they would still help them offload players.It's a dog eat dog world, competitors have no reason to offload Barca's dead weight considering they are absolute beggars right now with 0 leverage.
And Barça also missed plenty of opportunities to clear the mess :
- they could have not buy Aguero or Depay and them to pile up even more on the wage bill but they did anyway
- they could have sold Grizzi to Atleti weeks ago but they didnt
- most importantly, they could have sold Messi to City last year and literally solve the issue (a likely 100M+ transfer fee and Messi wages off the books) but they didnt.
Italian teams do it all the time between each other and that Pjanic/Arthur swap deal from last season was just a way for both clubs to balance their books. I've mentioned it before but Juventus exchanged Spinazzola to Roma for a 20-year old left back who they immediately loaned out to Cagliari and then to Genoa, no intention of ever using him. It was a book balancing deal and also I believe a wink-wink deal for Zaniolo in the future, but then Zaniolo had two ACL injuries.
I'm sure Barca could easily find a partial salary loan for Coutinho and Pjanic, find a taker for Braithwaite, been less demanding with Atletico in that Griezmann exchange deal, but like you said instead of doing that they actually kept bringing in players