The most charitable view:
To show western governments that the population doesn’t just blindly side with the Israeli government. A major difference between the two sides who are committing heinous acts, is that one side is a government committing genocide, and the other is a military organization (not the government) which was made in response to being forcibly expelled from their land by that government.
Neither side should be killing innocent civilians, but we should not be collectively taking Israel’s side, like is traditionally done.

The least charitable view:
Because people want to get away with yelling Nazi-shit in public.