The rules were changed in 1995. In order to be eligible for Tonys, a show has to have invited the Nominators AND the Tony Voters to at least 8 performances within the first 4 months of its run. If the show closes before those 8 performances are given, it is still eligible. CARRIE did not invite the Voters, and perhaps not even the Nominators, and so was ineligible.
As for Betty Buckley’s performance, yes, it was magnificent. Beautifully sung and totally committed to the nonsense onstage. Had the invitations gone out and had enough of the Nominators actually seen the show, she might indeed have been nominated.