Just the enormity in terms of length / duration of the third movement requires a mature level of stamina and mental focus. It is a tour de force. However any casual piano student can dish out some rendition of it. It is more accessible and the main thematic technique can be quickly learned and applied to the whole piece. Or , quickly hastily learned or not learned well but you'll be still able to recognize that they got the piece in their hand to some degree
10-4 has an entirely different assessment of difficulties. It is not highly accessible bc although at first glance the score doesn't provide any look of real difficulties, but as you go through really learning it you will encounter dozens , yes dozens , of different obstacles and problems you will need to engage and address whether successfully or not. Lot of it is things you need to do quickly in transition. This is a big thing. Especially if you want to make the piece sound like one seamless piece. Another is the working of chromatics that do not just run up or down in one continuous stream but are broken up you really need to delineate fingers negotiations at times Amongst other things.
At times I feel I can accidentally hurt my fingers on this piece and at all times I feel highly unstable when playing it. I never feel secure. Maybe it is just my progress level on it but I believe it is a universal feeling perhaps.