In reply to gimmergimmer:
Nah, this is BS, and here's why.
A tied-down belayer is not really different than a chonky belayer.
If your belayer gets ripped off their stance in an upward direction, that's probably more likely to upset your anchor than having and additional (separate) upward piece, you only need a single piece of up-gear because a full anchor isn't necessary for this.
If your gear rips, it was shyte gear. If your anchor rips, you wanna get better training. Possibly from someone else.
(me and my partner use ground/up-pull anchors all the time)