Because it sounds conceptually nice to good people, but selfish people know that without proper transparency and checks, it's very easy to consolidate power with it.

So the bad people get the support of good people and then exploit that flaw to do what they want instead of what is good.

It WAS as close to communism (actually socialism... though yes, the party was called a communist party and all that, but in reality, the name didn't really reflect the ideals of the party at the time, the name stuck for the sake of the Stallinists that were in quite large numbers and Tito and others were just trying to balance things out, since they needed some of those people to run the country and not turn their backs on them... some people were very cross with Tito when he turned his back on Stalin in the 50s, he didn't need to iritate them further by changing the name of the party) as you can possibly get at the time. No textbook representation of a social or economical system is 100% accurate to what the books say... just like democracy (which is basically anything but democracy at this point) is flawed everywhere.

The perfect system doesn't exist, but you can strive to make it better and serve the people, which is exactly what we DON'T have nowadays. Back then... to be honest, yes, it mostly served the people.