No, you don't need a tree stand. I think these are more important for bow hunters who need to get within about 30 yards or less of the deer to have a good chance of success. At 150 yards with a rifle, who needs a tree stand? I personally prefer the freedom and spontaneity of selecting a ground blind as I find a good spot. Just locate yourself where the wind blows your scent away from where you expect the deer to show, sit in shadow, break up your outline by having ground cover in front of you, wear something to darken your face to keep it from flashing as you turn your head (the face is highly reflective and "flashes" --turns from light to dark -- as the head rotates) such as a camoflage face net. Sit very still, move slowly, don't make noise.

Taking big bucks may be more demanding and may lead to tree stands, but for other deer ground blinds are effective.