All of the professional golf shirts, almost all Under Armour type sportswear are 100% poly - I was actually looking for a 100% poly button down - the only place I found one was in the sportswear dept (fishing) at Academy.
That's actually the trend for embroidery as well. It also has a much higher markup on it with regard to the golf shirts and embroidery.
Because they are also thinner as well, when I do digitizing for designs that are going on multiple fabrics, but they only want one design, I have to design to the poly one as that one is less forgiving then the others in most cases. Depends on the design as well.
Edit to Add: You have to be careful sometimes on how you wash these garments as well. Moisture wickering can be lost depending on what you use to clean the clothes. That's true no matter what technique you use to decorate it.