Al Deveron wrote:

Am I missing something?

About 30 years of fabric development.

Modern polyester fabrics are probably the best for outdoor gear. All of the
good fleeces are polyester. The best wicking fabrics are polyester. There's no
comparison between polyester today and polyester fabrics of the past. However,
you'd have to stay with the better brands to take advantage of these things.
There's quite a difference between, say, a good polyester T shirt and a poor
quality one - softer, better wicking and more comfortable.

Polyester also has better UV resistance than nylon, though that's rarely an
issue with clothing. However, tent flies are usually polyester nowadays due to
the better performance.

Mike