Antimicrobial treatments like silver ions or Polygiene are applied to ski socks to fight odor-causing bacteria, extending how long you can wear them before they get funky. They're genuinely useful if you're heading out on multi-day ski trips where washing isn't an option, or if you tend to re-wear socks between uses.
That said, if your socks are made with merino wool, you're already getting excellent natural odor resistance — merino fibers naturally inhibit bacterial growth. An added treatment is a nice bonus but not a must-have. It becomes more relevant for synthetic socks, which are more prone to holding onto smells without any treatment.
Just keep in mind that antimicrobial treatments can fade over time with repeated washing, so don't pay a huge premium for this feature. And no, treated doesn't mean you never have to wash them — your feet (and cabin mates) will thank you for regular laundry days.