Whenever these discussions come up, it is always mentioned that you shouldn't be taking high fall factor falls on a tether anyway, and doing so constitutes pilot error rather than a failure of a protection system never intended for such eventualities. The fact remains that there are situations in which a climber might have to make a move or two above an anchor they are tethered to. The pilot-error position says that those are "leader must not fall" conditions and the climber should view themselves as being unprotected.
Never a truer statement posted. Climbers push their gear much further than can be reasonably expected. The fact there aren't more incidents, I think, is an indication of how well the gear is holding up, not how poorly it performs because of isolated incidents.