I think your concerns are valid.
I don’t hike through brush with a light poncho. I pretty much use it to hole up under/in or hike to better cover in. I’d go with a heavier material wilderness innovations or a military poncho for busting brush if I wasn’t going to have real rain gear.
For me, If I expect to hunt in rain, I’ll definitely take a rain jacket and pants. Where the poncho fits for me is 2 scenarios.
1. Not expecting a long rain or to need a shelter, but I want something to ride out a quick storm or stay dry for an unplanned overnight. This works at a minimal weight.
2. I’m going somewhere really wet and want to be able to protect my breathable rain gear from wetting out. Still makes a shelter or windbreak too if I need that. Sometimes I prefer a seek dst or hyperlite tarp for this, just depends on where, when, and how many of us are hunting together.
A poncho or sheep tarp has been handy in AK as a “wall” on the cook tarp when the wind changes, as a windbreak, and to sit on, lots of uses.
I will take my old SEAK jacket and Yukon pants if I’m expecting major rain. I’ll take my Chugach jacket and Kutana pants if I want light rain gear. The poncho isn’t the answer to everything, just another tool in the toolbox.
Hope that helps.