It was utterly frustrating to be powerless to improve specification quality and find out you built exactly what was asked but you were asked for the wrong thing.
The silos were horrible. Devs were often as bad as BAs, dev’s just were just crapping on the testers instead. Spare a thought for the production ops person at the very end of the chain. Here comes 3 months of developer work in one weekend and no it doesnt work but we’re still going live because the entire tech org is invested in this release. Now you have smaller squads, you can postpone a release without it looking bad on the top person and thus affecting your career prospects.
In agile models you have the power to fix crap processes that don’t work. You can call out any BS on the retrospective and make it super visible when things are being swept under the rug.