Official comment
Thanks for your feature request, David!
There is a short list of role based email addresses in RFC 2142, but you're right; since 1997 that list has been expanded quite a bit by corporate usage to include many other departments. Ontraport isn't alone in blocking them from CSV import; most ESPs have a similar policy including MailChimp, Active Campaign and Infusionsoft.
But we'll take another look at this. Certainly your points A - C above make sense even if we don't allow import of role based addresses.
EDIT: Here is the list of role based addresses we are setting to "Transactional Only" if imported via a CSV file:
abuse@
accounting@
admin@
billing@
compliance@
devnull@
dns@
ftp@
hostmaster@
info@
inoc@
ispfeedback@
ispsupport@
list-request@
list@
maildaemon@
marketing@
no-reply@
noc@
noreply@
null@
phish@
phishing@
postmaster@
privacy@
registrar@
root@
sales@
security@
spam@
support@
sysadmin@
tech@
undisclosed-recipients@
unsubscribe@
usenet@
uucp@
webmaster@
www@