If I can put on my (probably red) zrick hat for a moment...
I am currently on an "all hands" webcast for my business unit in my company. Despite the fact that we do not have a single hearing impaired employee and CC is available because it's a freaking webcast, they have a sign language interpreter on webcam for the whole thing. I'm all for disability accommodation, but this is wasteful pageantry. I honestly couldn't tell you if it is driven by company policy or government regulation, but it's stupid and it bothers me more than it should.
If it is a private company, then there are zero regulations requiring an interpreter unless it is a meeting open to the public. If, of course, you have an employee that needs it, then you have to provide it as a reasonable accommodation.
Having an interpreter for an in-house webcast is foolish and CC meets most needs.
Your company is either too "woke", they had it for training purposes or they are unsure if any employees need an accommodation.
That said, there are some cases where an interpreter is better that CC, but it is really the responsibility of the employee who needs a reasonable accommodation to say "this is what I need".
A good company will have some sort of an agreement with a sign language interpreter company if needed - but it is beyond stupid to use them when not needed.