Base load is real by statistics. However it is otherwise a useless concept. People talking about base load are universally wrong - wind and solar work just fine even if they can't provide the base load they are talking about: because we don't need base load in the way they think we do.

Base load was a useful concept in the 1960s when the cheapest power plants couldn't follow load and so you needed to find the right mix between base load and the more expensive generation. Now that the old power plants are not the cheapest we don't care about it even though it statistically still exists.