Yes, Mark, I know that he thinks that way. It is interesting that when he comes to describe M. supertexta itself, it is initially described without location, with no floral description, and that in 1977 Hunt himself designated a lectotype for this otherwise somewhat incompletely described and therefore uncertain species.
Mamillaria albilanata presumably was properly described in 1939, although the oldest name for a member of this species group actually is M. ignota in 1839, post-dating supertexta by 2 years. The fact that Hunt ignored ignota as a name when he brought together albilanata and its 4 subspecies in 1977 might suggest some problems with that name as well.
It is quite possible that all the supertextae descended from a common ancestor, but that isn't a reason for lumping all of these species together. There are distinct features, but as there are no real rules as to what degree of significance these have, and where the line should be drawn, it seems it is anyone's right to give a plant a name, whether others accept or not. Common acceptance by peer group tends to cement in one set of names rather than another, but ther ewill always be dissenters.
It may be a while before DNA analysis gets to the level of sophistication of being able to separate subspecies. There will need to be agreement about what parts of the DNA are proper and consistent for analysis. Some parts might show up differences, others not so. What is significant about the differences will be the subject of as much discussion as taxonomic approaches. My personal view is that we will end up with a combination of DNA evidence and taxonomic evidence and this will improve our understanding, but because there are no absolutes, there will still be debate.
But as this example shows, if we can't trust Field Numbers, then where are we!! It still is the best way to collect them, and you can give the plant whatever name you like! You'll be more likely to be "correct" this way, even if there are a small proportion of errors in field lists.