As any activity gets more popular, the gadget inventors come along. With any idea pool, some are great, some ok, some terrible, some hit niche markets.

You say "old fashion" way, really? do you use a scope? heck do you use other than a patched round ball with black powder? compound bow? carbon or aluminum arrows? replaceable blade broadheads, rangefinder, safety harness, heck even a tree stand or blind?

all these are gadgets that turned out good. Gadgets that aren't good die off.

some things just make it a tad easier, or more conveinent.
Things like UA are designed for active use, not really hunting, well at least stand hunting. they are designed to help you stay warm despite working up a sweat in cold weather. They don't really insulate, they wick moisture away so you don't get chilled from the water. The stuff works, I ref LOTS of soccer games, starting in March when it's cold, wearing UA is so much better than not!

It's all evolution, and the mightly dollar. Take an everyday object and put it out in camo, they up the price, why? Why camo UA? It's always covered with other clothes anyway?