Not everyone uses them. They are not required and did not really appear until the 1990's.
Before that, we proudly used a wood hiking staff (not a "stick").
I've been using them for snowshoeing since the 80s. Indeed, early on we didn't think about using them outside of winter!
Nowadays, however, my knees and hips aren't getting any younger and I appreciate them more and more.
I have the black diamond non-adjustable Z-pole that only has one height. Makes them less likely to malfunction and probably lighter. They weren't cheap though.
Most important advice as you others have said: NO SHOCK-ABSORBERS. They make the poles feel less stable, make annoying noise, are a part that can be prone to breakage, increase the cost, and for the life of me I fail to imagine any actual benefit from them having them. What human joint is being helped by them?