The argument against that is that the best time to make a politician to promise something is when their job is on the line. The vote is really the only way normal Americans have to get their voice heard, and it, along with bribe money from lobbyists, is the only thing they listen to.

The other argument is that morally, many people can't bring themselves to vote for someone enabling a genocide. Especially since Kamala is connecting herself so much to Biden saying she'd do all the same things, a vote for her is a stamp of approval for all of the current administration's policies.

I've heard people say she has to support a genocide because so many Americans are pro-Israel, and she'll lose the election if she doesn't show unconditional support. That basically forces the anti-Zionist coalition to vote against her to show their numbers and prove they are to be listened to as well.