Not on a Daihatsu engine, but on many others.
The EGR valve is merely a valve which reduces emissions by allowing a proportion of exhaust gas back into the engine to be reburned. They are controlled in several ways, but are not normally a problem on many engines while they are young.

Older engines suffer from several problems with them, the main two being sooting up which occurs when people only use their vehicle for short journeys. Use their vehicle predominantly at low engine revs, or infrequently, or periodically use their vehicles.
Corrosion is the other major factor, most have an actuation rod which corrodes with time, and the excess conducted heat. This conspires with sooting to partially jam the rod caused by the soot jamming the valve, and not letting the rod operate properly. Or, the corrosion on the rod jams the EGR valve slightly open or shut.

To blank the EGR valve you need a proper plate, substantial enough not to deflect, and sealed fully to prevent leaks.

Is it worth doing? on an older engine, yes.