Does any of this really fuckin’ matter at the end of the day?

Yes.

Socdems for instance, have utility in certain situations but ultimately cannot be relied upon, allied with or really be considered apart of 'the left' in a meaningful way. This isn't puritanism, you just fundamentally cannot abolish capitalism with people who.. don't want to actually abolish capitalism. This is why Socdems are pretty infamous for betraying genuine revolutionary movements and aligning with incumbent forces of capital.

Odds are, if we’re being brutally honest here, none of us on the left, regardless of our faction, are gonna hold any significant power in our lifetimes anyway.

Defeatism is a irrational position to take. Do you truly believe that when the fields desertify and the oceans consume the coasts -- well within our lifetimes, unfortunately -- that the ensuing destabilization won't pave the way for an ascendant leftist movement? Fascism isn't truly a popular movement, only an ideology that adopts it's superficial trappings and masquerades as one, which is why virtually every Fascist regime in history only came to power by allying or grafting themselves onto existing state institutions with the assistance of the bourgeoisie, foreign or domestic. And while there certainly will be some nations that decide to redistribute the dwindling spoils, ultimately in most parts of the planet, when the people no longer have anything to eat they will eat the rich. Falling rate of profit also ensues the increasingly auto-cannibalism and collapse of neoliberal hegemony.

The real question is not whether there will be a revolution, but when. Before climate catastrophe or only after?