You do realize that coming up with slogans that aren't self defeating is one of the lessons that should be learned form this right? The plain meaning of the slogan does not paint a good picture. It doesn't matter what the actual message is, the slogan is awful and the movement desperately needs new messaging. I say this as a person who agrees with the actual message: a lot of money would be much better spent on things other than police and prisons even if you're solely worried about crime and don't care about police brutality at all.
Claiming that leftwing/progressive groups don't have anything to do with democrat politicians, even if they're not formally associated, is a fairly ignorant position to take. It ignores political reality. You might not like it, you might deplore the situation, but politics in the US is very much a team sport for a large section of the population. Messages like "Defund the Police" are a rallying cry much more than 1/2 the voting public. The problem is, it motivates all of one side (the right) and only part of the other, almost solely because it's such a terrible slogan and many hate having to defend and explain such clearly poor messaging. All this while scaring off ignorant independents who just see a bunch of racists and anarchists and are having a hard time choosing between the two. Stop making the decision difficult for the semi-literate.
Edit:So stop throwing bricks on top of them while they're drowning.