I'm running mid-80s Mavic G 40 rims on mid-80s Ofmega sealed hubs and had the rear re-spoked last year after breaking two drive side spokes in a season.

The only newer components, other than tires, tubes, and cables, on my mid-80s Vitus 969 are both derailleurs which were replaced when the Ofmega Mistral thermoplastic derailleur models failed after 20 years.

If it works, and you like it, ride it.

Perhaps the " worker in a bikestore" was looking to make a sale?