Well, look, this is a way to appeal to younger and up-and-coming voters, not seasoned longtime mid-age voters.
Younger voters (younger people in general) are often influenced by celebrities, athletes, artists, and idols who they may look up to...since this is Atlanta which has a pretty young demographic it makes sense why they brought Meg there however what Megan should've did instead of perform was give insight and perspective on her political views and why she thinks it's important to vote and particularly why she's supporting Kamala in the upcoming election, y'know a little monologue
That's something that I'm sure the people in attendance would have been intrigued to hear rather than seeing her perform. The issue isn't that rappers are used for appearances at political rallies, etc the problem is that we (generally speaking) don't know anything about them outside of their rap personality, if more music artists actually gave the fans/viewers insight on who they are and their perspectives on political matters the reception would be different.
Take artists like Ice Cube, Tupac, etc for example...Cube (a gangsta rapper) always gave an insight into what his perspective was revolving around politics, race, etc. Pac, when he was alive, expressed how he felt on certain topics; they weren't always in their rap persona but let the fans/viewers see the “everyday” side of them, a lot of artists nowadays tend to be in their rap personas 24/7 so we never really know much else about them besides the character on the musical track.