People like me
are hidebound by tradition and cost and have galvanised wire that lasts for ever (those lower shrouds, parcelled and served full length, date from 1977; the rest dates from 1985) but the racing smack owners are unconstrained by cost and tend to feel that getting ahead in a race is worth more than tradition.
I suspect the answer may be either UV degradation, chafe or "creep" - I understand the first two but not the last - someone here is bound to know!