That's a over simplistic view of power production. Companies don't build generation resources because of MWhs. They build because of capacity shortages. The problem with renewable sources is they don't consistently provide capacity. They mainly provide energy (MWhs). That's why battery technology is so important. Unless that energy can stored and used later to provide capacity, then renewable energy has huge limitations. Even beyond that there are serious problems. From my professional discussions with power production engineers, there must be enough initial inertia to power certain industrial infrastructure, such as an arc furnace, for example. A battery does not have the capability to power a 200 MW arc furnace because it lacks the initial inertia to power it. It requires a high mass spinning rotor in order to keep it running. While technology is improving, there is still a lot to overcome before renewable sources can truly replace fossil fuel sources.
Interesting but throughout history as new technologies develop, challenges come with them, but we find ways to meet and resolve those challenges.
Compared to the complexity of equipment and the staffing needed to build and operate a coal-fired steam plant or a nuke plant, it's obvious that the simplicity of a solar farm or an offshore wind farm has potentially enormous economic advantages, notwithstanding the advantages regarding climate and health issues. The idea is not to flip the switch some day and turn 100% of our energy needs to renewables, rather it's to move as much as we can as quickly as we can in a safe, efficient and competent matter. As grid and battery capacity improves along with other tech improves we can do more of that.
We will always have some need fossil fuel products. Kerosene to power jet aircraft, petroleum to manufacture vinyl used in cars and furniture etc., nat gas to power generators in places where alt sources are impractical. etc., and petro-chemicals for manufacturing and agriculture.