I started riding in my kitchen about 1980. Kreitlers. I had the fan, but didn't use it. We were doing testing for things to stabilize rollers. I live in SoCal so rollers were for low resistance. At the time roller competitions were a thing - a small thing, but they existed.

I got my kid on them about age 10. I'd dump him on the side of the road before a race to warm up. At that time he couldn't dismount without help #meandad.

Portability was a nice feature too. Took the train to Wi for nationals in 2013 and he got his riding in. I've posted this numerous times. Also - not the same as the road, but you CAN stand on rollers.