In my experience they usually are worse than useless. As in they have negative productivity and actively harm the company.
For example, marketing at a previous company was extremely incompetent. Everything they did was basically a major cringe-fest for everyone involved. They would send a company-wide email announcing they had made a 'viral video' and if you could please share it as much as possible. The aforementioned video was super-boring and about corporate stuff no normal person would ever care about. How the hell is that supposed to be a 'viral video'? Apparently they completely lacked the capability for self-critcism.
They also did fake-interviews with members of upper management, the whole thing was so obviously scripted and read to the camera that you just had to feel ashamed for them. They also made rookie mistakes like looking directly into the camera and stuff like that. The resulting videos looked extremely amateurish, the average youtuber has a higher production quality.
HR did more harm than good, their main role was to get rid of everyone who had any knowledge of the product and anyone who was critical of management, basically what they wanted was yes-men.
Management itself was completely retarded, to the point where the whole C-level was fired by the board followed by several lawsuits. They kept interfering with engineering decisions not held back by any knowledge on the subject. They basically forced us use certain tools that would result in a lower quality end result, take more people and take more time, and thus be more expensive for the customer (and harder to sell). All purely for political reasons; and then they wondered why they didn't make any money.
Of course, as a software company you want to spend as much as possible on managers and as little as possible on engineers, so that is what they did. This of course attracted the kind of manager who only does it for the money and status.
In the end, the company went belly-up. Apparently you can't survive selling an inferior product for a much higher price than much smaller, leaner competitors did. Especially if your organisational structure is diamond-shaped.