Why Engineers Hate Their Managers (and What to Do About It)

i feel strongly that most managers are redundant

you could have an empty chair and things would still get done

in general there are too many useless or noise making people in companies i worked in

when they go on holiday the work continues in peace

Things might get done, but would they be the things that the company's upper management and investors want done?

yes, why not.

remove upper management too. problem solved.

Engineers should be talking with customers at least some of the time, so that part is covered.

There is the strategy side of things which you won't get from talking to customers, but I've seen many cases where senior management make absolutely terrible (and obviously terrible, not only with hindsight) strategic messes, so I'm not totally convinced that senior management are necessary for this part either. Senior management do usually have a better overall picture - eg. that some product is losing money and some other product is growing rapidly - but that's usually because detailed revenue numbers are hidden from everyone below the C-suite.