Well, this is somewhat true in the wild as well. As long as they
propagate themselves it is not an issue.
I got a single seedling of S. oreophila (not collected) several years
ago, and as a result of division from that plant, about 6 more people are
growing it in the area, including the person I got it from in the first
place (so he now has several clones).
Now if an area were to be "developed" (blatant euphemism if you ask me)
and all the plants were destined to oblivion, then any plants collected
from the area are last reservoirs of the gene pool, and should be
collected. (Isn't this the case with S. flava atropurpurea?)