Polycotton is a very good and very under-rated outdoor material. Here's some reasons to consider wearing cotton or polycotton on your hikes this summer:
>Extremely affordable
You probably already own it.
>Tough & durable
>Also soft against the skin
Two traits merino wool can never have.
The only natural fibers with these traits are exotic, expensive, and its very limited what you can make out of them due to their staple length.
>Does not get swampy and feel gross when you sweat like 100% polyester.
>Does not take 2 and a half days to dry out like 100% cotton or merino wool.
Another unique advantage. One of the best feeling fabrics to wear in the summer.
>Muh cotton kills
Doesn't apply at all here. Especially not during 3 seasons if your rain gear is functioning.
>Available in almost every weave pattern owing to varied staple lengths
You can make anything from a thick canvas to a silk-like mesh out of polycotton. And it will be strong.
>Muh plastic
Most merino wool on the market is spray coated with plastic resin to shrink-proof it. Most anons don't have the budget to buy exotic fibers or alternatively/un-treated merino so its existence is sort of irrelevant to them. I recommend them all the time and very few anons actually buy gear like that. Coarse wools are available like this readily, but would mostly be used to make different garments than polycotton would, so no sense in comparing them.
>Plastic shedding
As long as you stick to garments using tight weave patterns and longer staple cotton, it won't shed plastic everywhere you hike. There's garments made of this stuff that shed and ones that don't. Think: a fleece vs twill or canvas.

Disclaimer: I only point out shortcomings in other fibers to highlight polycotton's strengths. All fibers have their niches I use them all including exotics. Don't make this another shitting on wool or shitting on polyester thread.