That’s usually not true. Most people are purged because they’re supposedly dead or moved. Those people usually aren’t voting (in that location) anyway, so failing to purge them does little. Even for people who might actually vote there, such as felons or non-citizens, they face severe legal consequences for voting when they’re not allowed to, even if registered, so they usually won’t vote either.

Incorrectly purging people is way worse than incorrectly not purging people.