Are they there to be communication and documentation experts, or are they there to turn requirements into something that works?
I agree that there is benefits in having engineers who can engage with their managers, advocate for required changes and influence the management to act in a more beneficial way, but at some point the person doing this stops being an engineer and starts being a manager themself.
Managers are there to manage, that is organise, coordinate and ensure that their staff are completing tasks in the most efficient way possible. That will at time require them to communicate with both their superiors and their engineer staff. That requires them to be the the communication and documentation expert, not the engineer.
Worse, those that are good at talking are going to waste everyone else’s time.
I said half because that seems to align with the marketing budget vs engineering budget, so it might be the best spot for companies as a whole.
Whether engineers do or don't do documentation and how much of it is decided by management.
Second, unless you are specific, I will assume the "improve their communication skills" is purely stereotype based. They are engineers, therefore they do not have communication skills. And we are going to pretend so even though they just communicated what they need very very clearly and politely.