Using wheeled vacuum heads on vinyl liner - Why Not ?

Hi Everybody,
New guy to this Forum, I am a 15 year old veteran of DIY care and maintenance of my 36,000 gal, free form, IG vinyl pool.
I would like to know why it's not recommended to use wheeled vacuum heads on vinyl lined pools. The one I'm especially interested in is the Pro Vac 214, also know as RB214,...with the urethane wheels and ss ball bearings.

I've only found a few articles on the internet saying they're okay to use if you're "careful, but don't specifically point out what you have to be careful about. I've found a LOT of articles that say DO NOT use them on vinyl liners, but again, don't say why.

I joined this Forum hoping to find an answer to this question. I have seen them in action and even tried one out, they seem AWESOME.....Any help out there ?
Thanks, Mike