Today (April 5th, 2020) at 9:00 PM IST, people across India are expected to switch off lights for 9 minutes.

This has apparently raised concerns that there would be problems to the power-grid, due to under-utilization of power.

Can any one explain this (in layman's terms)?

a) Specifically, will the generator be overloaded and stall because the power lines will eventually be saturated and achieve the same potential as that of the generator (given that energy flows from a source of higher potential to that of a lower potential)?

b) If it is the case, is there no control to simply reduce the amount of power generated to match the consumption?

c) Or is it the sudden decrease in power consumption that is the cause for concern?

PS: There is a similar question here - Why does the frequency of power generation change when there is a change of load on the power grid?

But I'm looking for an explanation that can be understood by a layman.