What experimental facts served as the basis for the hypothesis of the complex structure of protons and neutrons?

If a proton and a neutron can have different excited states in the form of hyperons, then it can be assumed that these particles themselves are not “real” elementary particles, but consist of some even smaller particles. This assumption is confirmed by the results of experiments on the study of the scattering of very fast electrons by protons and neutrons. In these experiments, it was found that most of the electrons pass through protons and neutrons without experiencing significant deflections, and a small part of them is scattered at some centers. This result is similar to the results of Rutherford’s experiments on the study of alpha particles passing through atoms.