> "To what degree should we defund the police? And how else might we limit their power?" are perfectly germane ways forward with a discussion.

You're completely correct, and it's a topic that the US urgently needs to have a serious, non-inflammatory discussion about. And that's why when you start off with shouting slogans:

> ACAB. Defund the police.

you get a response which is not one of the "perfectly germane ways forward with a discussion." Because the way you began things doesn't sound like you want a discussion. Maybe lead off with something that still gets at your point in a more productive way, e.g.:

> "To what degree should we defund the police? And how else might we limit their power?"