And there is also night. And clouds. Texas is good for solar but December and January still have relatively high variance - for example, in December 13 solar produced only 19.3 GWh while it produced 103 GWh two weeks later on December 27.
No single source has ever provided all electricity for any major region. To pretend otherwise is disingenuous.
Fossil fuels have done that trick, long before gridscale wind and solar ever existed.
So really you're the one being disingenuous.
Fossil Fuels aren't all one thing. There are different types, with vastly different infrastructures, etc.