It's more that the consequences of a management fucking-up have many times the impact of the consequences of the fuck-ups of individual members of the team, because a single manager's choices impact the work of multiple people.

Further, managers who do things like setting the deadlines themselves, actively pushing the devs to lower their estimates of the time it takes to do something or, even better, actually take a junior developer's estimations at face value, are the ones responsible for the deadlines and thus to blame when they're missed - if in some way or another you forced certain deadlines on the team or fully trusted information from the least knowledgeable, it's on you, not on others.

Some managers are actually pretty good in that they don't do that kind of shit and even properly manage things like client/external dependencies, but in my experience they're a minority.

Granted, when the deadlines are missed for such managers it's not usually their fault: sometimes it's the devs' fault and others the fault of somebody upstream in the process (such as the client, an external provider or a business analyst).

That said, I can see where the stereotype about managers fucking up projects would come from, especially in certain countries where the management culture in Tech is one of bullshit, incompetence and even bullying, so they have way fewer competent managers and way more abuse than countries with better management culture in Tech.