A setting already exists to determine default frequency of digests for all new users, including “never”.
What is being complained about is that people forgot to set it at the time the site was created, and it is not retroactive.
I would be very strongly opposed to digests being pulled out, since most people sign up for a community site and then promptly forget all about it and never come back. Mailing them your “greatest hits” at some regular interval – again assuming you realized this setting was there to tweak at the time of installation – is quite critical to getting people to come back at all.
This is a big part of “it just works”.
But I definitely support suppressing further digests for people who haven’t been to the site at all in 365 days by default. Much safer.