Not useless/pointless/etc. IMHO... but
almost so. Danged close, in fact.
Leaving breaching out of the equation (agree 100% with prior comments re: the silliness of this outside LEO/MIL applications), a PGO shotgun has a very narrow applictaion in HD scenarios where (1) the shooting will be at minimal distances, (2) the weapon will be fired from a small, confined space, and (3) a folding stock, even if available, would not be deployed.
My own wife's defensive position/role if the alarm should go off in the night
used to be (before we had children) to grab her shotgun and retreat to the master bath's tub with her cell phone to call 911 while I defended the bedroom/hallway point of ingress from behind cover. Her sole duty, once the call was made, was to remain in the tub and destroy anything that tried to come through the bathroom door that wasn't me. Inside the tub enclosure, the PGO shotgun made sense for her, and she practiced with it enough that I felt comfortable in her ability to defend the doorway at that distance with her shotgun.
The argument could be made that you give up nothing by using a side- or top-folding stock with a PG and then it is there if you can deploy/use it, and it is a sound argument... except that we discovered very quickly that the mostly-horizontal "witness protection" style PG for a shotgun is far superior to the routine vertical PG found on most PGO shotguns and all folding-stock shotguns.
Here is her pet 870 back then, in case you aren't familiar with the grip I am referring to...
It aims quicker and better than a vertical PG IMHO, and the recoil is far less jarring to your wrist and much easier to control. If you've never tried one and wish to keep a PGO shotgun around, I highly suggest you try one (I believe SpeedFeeed still makes them).
Anyway, we eventually had children and her role/duties in an HD scenario have changed. Now she corrals the kids into the tub and defends the bathroom door from a position beside, but outside of, the tub enclosure -- so now she doesn't have the confinement excuse and I finally talked her into using a stocked shotgun instead. This is what she practices with/keeps for HD now...
IMHO, this 870 is far superior to her PGO one for a wider variety of uses and fits her current HD role very well.
So, very limited applications with severe utility limitations? Absolutely.
Useless/pointless? Not quite.
YMMV, as always.