I don't think cutting an anemone in half to make two is in general something to object against. It is for sure better than taking them from the reef.
Keep in mind that for every anemone that is taken from the reef you also loose a pair of clownfish in the wild.
But with cutting anemone you cut a single poly in half and you always risk infection and loss. And so far - to my knowledge - it is only done (successfully) with Entacmaea quadricolor (BTA) which are the lesser threatened species in the wild.
I don't know if this propagation method could also work for the other important host anemones Heteractis crispa (12 clownfish species), H. magnifica (12), Stichodactyla mertensii (12), S. gigantean (7) and S. haddoni (6). I myself would be very hesitant to cut one of those in half. With those I would rather try to artificially induce spawning.
But for sustainability we need to find a way to propagate these in captivity too.
Fragging a coral is a bit of a different thing as you don't cut a single polyp in half but separate a polyp cluster.
In any way I think fragging is in general a good thing as it allows to easily propagate corals in captivity and therefore limits the need for harvesting corals from the reefs.
And it is hard if not impossible to match the light and current flow for a large wild coral to what it had adapted to on the reef. But the fragments can much easier adapt to a new location and grow accordingly.
I tried to keep corals in the 90s but it was always hit and miss. I only got a few to survive and grow. But now I have so far not lost a single fragment and all are growing.
