Question

Why Pendulum is not used for measuring time.

Answer 1

no this not correct..The pendulum is an excellent way to measure time.
It is simple, no tricky things required.
And most important, the swing time is not dependant of the power you apply to drive it. It might swing further but the time will be the same.
In the formula there is only the length and gravity.
Disadvantage, the base has to be stable but a clock tower i.e. will do.
On a ship it is useless