Because such majority is not guaranteed forever
It would be if everyone entitled to could easily vote. The GOP is running on policies far too unpopular to win without voter suppression and on never changing those policies no matter what.
The problem for the Dem leadership is that, just like the GOP can only win by disenfranchising people, right wing Democrats can only dominate a party that has drifted left without them if voters are scared of the greater evil that is a Republican with any chance of winning.
THAT’S the real reason. Voting being representative hurts the power base of the center right to right wing Neoliberals in charge of the Dems almost as much as it does the fascist Republicans.
It would be if everyone entitled to could easily vote
Well, that is like saying “in a perfect world…”. Today Americans do not live in a democracy where everyone entitled to could easily vote. And there are MANY reasons for that, not just one type of obstruction.
