As someone else mentioned with one (notable) example, any trans' person who does that is actually rejected under the label "truscum" (The opposite of truscum being tucute, obviously). It's not even that rare a position either, especially among the older (and, separately from them, the more successful looks- and most likely mentally-wise, it seems like to me) trans' people.
But just like with many social movements, once the rational part of the group has reached the point it sought (In this case, access to transition and all, with safeguards), only the looney part is left pushing "forward" (for transition without safeguards, for non-binaries, and all that jazz).