The theory is fairly broadly understood.  The practice is well documented and observable...and typically abysmal.

I used to consider myself a 'Socialist' back when I considered the term to mean just society working together to build a better life for all.  When I realized that the 'new' definition was command control of the economy and means of production I ran screaming.  When I grew up that was called Communism (and without exception resulted in a nightmarish a dystopia.  And rapidly.)

Bait and switch.  Just like 'vaccines' which, once indemnification laws were put in place for them, were re-defined so that almost any medication can take on that label and legal protection.

I've read that 'Left wing' relates to the devil sitting on the left shoulder, and Leftists (at least now and probably before also) seem to take delight in lying and deceit to achieve their goals.  At least much more-so than your average right-wing reactionary who are considered 'slow' and 'stupid' by the intelligentsia leftists/pinkos.  It's something more than simple mental deficiencies which make a person prone to honesty, and a lot of the reactionaries understand the pinko ways and means just fine.  That's why  I don't really mind being mistaken for or labeled a 'right winger' even while a lot of my preferences and philosophies are hold-overs from my 'socialist' years.