If you have a plant that can make 100 MW continuously then that is what you do with it. Unless someone is going to pay you to turn it off, you keep it running.
Depends on if you're considering the generator perspective or the grid perspective.
The grid doesn't simply want megawatts. It wants a balance of supply and demand, and a minimisation of outages.
Wind and solar cannot be spun up on demand. Hydro can be, and in general is (much lower-capacity hydro is grid smoothing). Hydro will even suck capacity off the grid where possible (pumped storage).
Geo which can load-match, disable when grid is oversupplied, and fill in for cloudy & windless days, makes all kinds of sense at the grid level.
With geothermal, though, you don't actually want to run flat-out all the time, as the geothermal reservoir does require time to recover, whether that's groundwater refresh or heating up after a period of high generation which extracts heat faster than it is transmitted through surrounding rock (most cases) or magma (not yet a major utilisation mode).
Soaking up excess generating capacity through interruptable heavy loads is somewhat better suited to wind or solar. If you have a task you can divert electricity that will be generated anyway to, so much the better. That's what pumped-hydro, desalination, grid-scale battery banks, or fuel synthesis represent.
The grid doesn't simply want megawatts. It wants a balance of supply and demand, and a minimisation of outages.
Wind and solar cannot be spun up on demand. Hydro can be, and in general is (much lower-capacity hydro is grid smoothing). Hydro will even suck capacity off the grid where possible (pumped storage).
Geo which can load-match, disable when grid is oversupplied, and fill in for cloudy & windless days, makes all kinds of sense at the grid level.