But, SS stanchions cost money!
FWIW...
I have observed a number of sailboats, from diverse builders, that seized the "usually single wire" life line to the outer shroud at that part of the side deck, in the 60's and early 70's.
At some point the buyers must have become more willing to pay for a more detailed-out stanchion system.
Of course, back in those halcyon days, pulpits, lifelines, and the anodizing on the aluminum spars were extra-cost options...
By the late 70's, I still remember the arguments, both ways, at a PIYA meeting over whether racing boats under a certain length (about 18' as I recall) should have life lines and whether stanchions over 18" high should be required.
Both the standards of the industry and the sophistication of the buyers have changed (and occasionally improved...) since those days.
Loren