It would probably be worth paying/staffing whatever though since people may do something for free, but it may not be enough to make a happy end user.

Not all companies miss this, Amazon has strict SLAs on responding to user requests, and this even includes GitHub issues. Personally, I find it rare, though not non-existent, to have a good experience with Google customer support or OSS while Amazon generally feels pretty good. Maybe just lucky of course but the brand effect is obvious to me and perhaps worth the companies spending a bit on.