For what it's worth, I spent 25 years in the games industry working with the biggest companies in it and I can tell you flat out that many of the games we helped develop (we were these company's QA source) cheated as a way of dealing with skill levels high and low. Gnubg in my day would have never been put out as a boxed product for sale (yes I know that isn't how it's designed). It would have simply been too insulting to the general customer as presented.
The way it likely would have been handled would have been to create an interface that highlights the lowest AI levels calling them things all the way up to say, "Expert" even though it would maybe be capped at what we know as Intermediate. The higher levels would then have all been called one thing ("Professional" perhaps) with a slider to set "how professional". That would give the average customer the sense that they are only, on average one or two "steps" away from being amazing. Perception is essential even if it's not accurate. This would also cut down on the cries of cheating as most people would never bother to go beyond "Expert".
I'm a big fan of the product so this is all just for perspective purpose. I would say that maybe it might be an approach for some new UI "skin" approach someday, if ever.
Why? Nearly everyone I put onto the product gives up on it as they're used to turning skills up and are also put off by all the daunting terms they encounter. It works for all the serious people but there are never enough of those to make a product as popular as it could be, usually by a wide margin. Worse, a sort of bubble sets in as new ideas only come from that community. Most of the time people are not able to see beyond their own needs so the product just becomes more and more painted into an ever shrinking corner space.