Waterfall absolutely was practiced. Budgets always overrun and developers had to work overtime to meet deadlines completing all the tasks that weren't mentioned in the plan.
This still happens under agile too. It’s not like a process magically fixes things. Most of the issues I read from SWE in regards to agile is that they are often neglected in both decision making and the ability to hold leadership accountable.
No amount of agileness is going to save you from a miss managed team.
Well I wouldn't count mismanagement against agile then. At my work we practice SWE by managerial dictatorship and also "agile." I'm certainly not holding the failures against agile.
No amount of agileness is going to save you from a miss managed team.