Reinhold Messner used trekking poles and he is renowned for making the first solo ascent of Mount Everest without supplemental oxygen. There are not many in this world who are even near being in his class and he used trekking poles.
If I am off pavement I have my poles with me in my hands unless I am scrambling. They take me further and faster as well as safer over rocky, hilly terrain, mountain trails and canyon country. Around camp or lengthy rest stops in hot sunny weather I use them to make a shade shelter with my tarp, a bit of line and some MSR Groundhog stakes I keep in my pack. They probe the rocky, plant covered terrain in front of me for sign of snakes. I can vault over small creeks or from rock to rock.
They do take a while to get the rhythm and the hang of them but after many years both girlfriend and I use them on every kind of terrain.
I don’t think there is any doubt that they will benefit even strong hikers but preference is another thing. Some people don’t want anything in their hands no matter what the benefit may be. Some terrain, at least, calls for them to go on the side the pack, out of the way.