The level of detail is part of it. The inherent speed of analog on a large range of numbers is the other part. I recall early efforts to model analog circuits l

The level of detail is part of it. The inherent speed of analog on a large range of numbers is the other part. I recall early efforts to model analog circuits like digital gates overwhelmed the computer. One circuit with 9 transistors took over 50,000 equations or something to check. It just did that much. This is only true when they're doing the things they directly implement like filters or differential equations. They run faster at fraction of size and power.