"Good" isn't a natural phenomenon that just needs a little space to establish a foothold. It takes deliberate action, effort, and sacrifice. And society doesn't magically reach a stable state. That's ridiculous.
Each election may have a bad and a worse outcome, but it's relative. Voting for the less-bad is a strategy that works even when both parties push toward evil. It works even when the choices are a party that supports genocide quietly and one that supports genocide loudly. If the "practical left" is just voting for the less-bad, while shitting on and shunning the people trying to do the hard work because the magical Fairy of Good hasn't yet shown up to establish that foothold with a wave of the wand, then I question how practical and how left that faction actually is.
That's funny, I seem to recall an Uncommitted movement...