I’m just grateful that actual leftists 80 years ago didn’t have qualms about killing fascists.

This just shows you are unfamiliar with the history of successful movements, because they absolutely didn't start killing randos when they had virtually no social acceptance, and there are numerous famous cases where communist parties denounced members who killed people at inopportune times. I'm talking about actual communists who fought guerilla wars.

Usually the only groups that ignored considerations of what is acceptable in the current situation and what their power was were certain anarchists and rather marginal maoist groups, and they never worked out well. Like I said, cops and secret services all over the world literally have people do this shit sometimes to fuck up movements and have an excuse to crack down on them. I don't understand why we should afford them their luxury to do it on ourselves.