My experience has been that if someone is analytically inclined, and willing to put in honest work with a trainer and on their own doing homework, that an intermediate ammie with good basic riding skills can get good results and fix problems in their horse. They can end up exceeding what they thought they were capable of.
The program does tend to attract riders who have hit a roadblock in their current program which may be why we see so much emphasis on going back to basics at least for a short period of time.
Beginner riders in lessons can also learn some basics early on, like shoulder fore and shoulder in at the walk, when they have basic skills mastered.
But yes, like anything novel, legerete also attracts the not very good riders who hop from program to program looking for a quick fix, but aren’t ready to commit to doing anything well. And there are a few pitfalls they typically fall into. If you don’t have independent seat and aids and good timing and the ability to maintain contact, it can be hard to get some of the techniques for reaching for the bit to be effective.
These exercises aren’t that difficult but it is very hard to get the right contact without some in person instruction.
Now that American and Canadian certified coaches are appearing, anyone interested could look to audit a clinic by one of them, much less pricier than getting the visiting top level coaches from Europe. There are also coaches still in the teacher training process who are teaching the method, especially in the areas close to the teacher training clinic sites.