Why can’t muscle and nerve cells, combined together, be called tissue?

In biology, tissue is a collection of cells and intercellular substance, which are similar in origin, structural features and functions. There are 4 types of tissues: epithelial, connective, nervous and muscular. Now let’s get back to the task. Nerve and muscle cells are mentioned here. Since these species differ greatly in function, structure and origin, they cannot make up one tissue. Nerve cells form nerve tissue, and muscle cells form muscle tissue. And already these tissues, of course, can contact as part of organs and systems.