Yes, a guess on your part. And a wrong guess. Before V2, it wasn’t a concern about “identifying Catholics” because Catholics themselves identified whether they were or were not in communion with Catholic teaching. They excused themselves from official practice if they were not. There was no Entitlement mentality to re-define doctrine for oneself, by virtue of some “membership card,” not to mention selecting which doctrine was or was not comfortable to adhere to, because the Magisterium, not the individual, was recognized as the Central Authority.
The concern is not the membership card. The concern is the what is espoused. If the pronouncement does not conform to authentic Catholic teaching, the statement is not a Catholic statement, even if the Pope officiated at that Baptism. Yet modernist Catholics declare autonomously the privilege to identify “what” is Catholic, based on who is Catholic. There’s too often a chasm between the two, a chasm which in the not-too-distant past, was virtually closed.
Have a nice day.