The most frustrating aspect of Leftists is their ability to be on the right track, and totally fuck any hope of making progress by capturing the cause, wasting all the availability money/manpower on nonsense, and stonewalling any attempt to work around them
police brutality and general pig behavior is bad
Leftists consistently choose arguably justifiable or even totally justifiable instances of use of force while ignoring clear brutality because they're exclusively concerned with minorities. bootlickers make short work of leftist arguments because they've yet again decided to try and argue Quanderious Washington charged that cop with a knife because of socioeconomic factors
environmentalism in general
Leftists care exclusively about climate change and insist the only solution is taxation. When all our pollinators are extinct because of carpet bombing pesticides Leftists will insist it's our fault for not paying the government to make the weather good.
Healthcare
socialized healthcare is literally unfixable because leftists will never criticize the system under any circumstances. The closest they get is complaining that it isn't socialized enough. If you complain about literally almost dying exclusively from healthcare staff incompetence/indifference, the only way you could possibly think the system is broken is if you're a hitler nazi