I use Zwift with a Tacx Vortex Smart Trainer and find it just fine. I can’t imaging doing the mountain without automatic resistance!
I also have a a Life fitness Lifecycle C3. I notice it’s not in the list of supported trainers and I’m assuming it’s not usable with Zwift. Just out of interest, has anyone used a Lifecycle with Zwift with any degree of success? Is it a complete non-starter?