You are correct that the wave-particle duality and the probabilistic nature of wavefunctions apply to all fundamental particles, including quarks. In quantum mechanics, the state of a particle is described by its wavefunction, which is a mathematical function that encodes information about the probability amplitude of finding the particle in different states.
However, the reason why discussions of wavefunctions often seem to focus on electrons is primarily due to historical reasons and the prominence of electron-related phenomena in everyday experiences and basic atomic physics. Electrons are familiar particles that are commonly encountered in macroscopic objects, and they play a crucial role in determining the chemical and electrical properties of matter.
Moreover, the study of electron wavefunctions and electron behavior has a long history in physics, dating back to the early developments of quantum mechanics. Experiments like the double-slit experiment and the observation of electron interference patterns have been pivotal in highlighting the wave-like nature of electrons and the significance of their wavefunctions.
While electrons receive more attention in popular discussions of wavefunctions, it's important to recognize that the same principles apply to other particles, including quarks. In the context of quarks, wavefunctions describe the probability distribution of finding quarks in different quantum states, such as their positions, momenta, and other quantum numbers related to their fundamental properties.
In recent years, as research in particle physics and quantum field theory has advanced, there has been an increasing emphasis on discussing the wave-like nature of other particles and their associated wavefunctions. As our understanding of the quantum world deepens, the broader discussion of wavefunctions and their implications for all fundamental particles will likely become more prevalent.