I don't accept that. You clearly know nothing of the social/working movements of the early 1900s. The hallmark progressive achievenments made in this country, many that still exist today (to varying degrees ofc) were a result of literal blood, sweat and tears from third parties.

The Progressive Party led by Roosevelt, The Bull Moose Party with social reformers like Jane Addams and Florence Kelly, the Socialist Party of Eugene Debs.... all of these were most prominent in fighting for and ultimately producing a cluster of social welfare, social insurance reforms, women's suffrage, workers rights/5 day work week, etc.

It was the dedication, pressure and will to not fall in line trying to change the two-party duopoly from within but to build their own movements, their own coalitions on the outside, and thus the mainstream parties were eventually forced to inscribe the populus demands into legislation.

Healthy third parties are a good thing. It builds actual pressure on your legislators. Politicians wont work on your behalf when they know you're voting for them anyway — they're lining their pockets with money from the bourgeois they actually legislate for. Seeking the change you wish to see via third party can and has produced monumental value for the working class.

But sure continue spelunking and misplacing your frustrations on your fellow worker instead of holding your desired candidate/party accountable for their bs offering. We'll keep climbing that hill in the meantime.