I think I understand this issue well enough to comment and so I will.
1) I totally believe it is reasonable to consider operational challenges
when designing protocols. "Just upgrade your infrastructure, just use
another registrar, just upgrade the infrastructure of the people you
communicate with," are not generally reasonable advice to give people;
ingoring these concerns tend to lead to things that cannot be deployed.
2) I think it's fine to come up with a solution that is harder to
implement because it is easier to deploy given the sorts of concerns in
1.
3) having reviewed the DNS arguments, I generally would recommend txt
records with distinct owner names over new RR types for most
protocols. I understand there are residual issues with that approach.
4) Using txt RRs the way SPF does--where the owner name is shared
potentially with other applications is kind of unfortunate. I don't
know it's unfortunate enough to push for the SPF RR. But the issues
people have brought up with regard to updates and RR order are very
real.
But so are the operational issues with SPF.
So my personal opinion is that this is a valid discussion to be having
even if we're having it again in IETF LC. However, to be successful we
need to get new participants and to ad more respect for arguments to the
discussion.