You misunderstand the point though. Sure there is always 5GW of demand - but we don't need generation that always supply 5GW cheap since wind/solar is much cheaper for base load. What we need is non-base load generation that can jump in at a moment's notice when needed because wind/solar isn't enough. Previously we would use those peak plants from when there was 6GW of demand (or whatever), but now between those peak plants coming down in price and wind/solar being so cheap we don't want that 5GW from plants that cannot adjust to load anymore - we are getting the can't adjust to load from wind/solar.