I see both sides.
On one hand, you're right, there is no point apologising because it will not make up for anything.
But an apology, provided it is a sincere one, can help.
I've not heard an apology yet from anyone that was, in my view, sincere. They have been "I'm sorry, but, i didnt know - i was only a small part - i was only followimg orders - excuses excuses excuses"
If it was me, I'd like to think I'd say something like
"I'm sorry. I have caused you untold pain and hurt.
I am going to be truthful and answer all questions to the best of my ability. Some of what you will hear will be very painful and I take full responsibility for my words and actions"
And then actually do it - even if it is embarrassing and I now regret the things I wrote/said in emails and meetings.
For example when PV got caught with that email about being bored watching the One Show and Jo Hamilton was not passionate.
She did say sorry, but then started with the excuses:
"I was under pressure/stressed"
"It was a mistake, I'm not like that"
"I didn't mean it"
She should have just stopped at the apology and there explained there was no excuse for her words and behaviour.