I don't think anybody wrote a description of a classical computer that excludes components that generate harvestable random noise. Effectively all computers are probabilistic, it's just that the probabilities for instructions, memory fetches, bus transfers, etc, have such low error probabilities that you will likely go years without directly observing one.

A classical computer is a pure mathematical object. No real-world computer completely embodies the concept, but they vary in how much they try to hide it. Rdrand is an admission that no they're really not classical computers, and it turns out that that is useful in certain scenarios.

oh you're talking about deterministic turing machines (have not heard that referred to as "classical" computer before- typically when people say that, they mean an actual physical real-world computer, not a theoretical model.