Communism has never been tried at a large scale. Soviet Union didn't have it. China doesn't have it.

Just because someone has "communism" on paper doesn't mean the society actually functions according to the communist idea.

Social democracy has been tried in many places and it has produced things such as the Nordic Model and the Nordic states that have been very successful.

After the 2nd World War USA was very close to socialism. High wealth taxes, workers unions etc. As a result your average worker had a lot of purchasing power which of course fuels economic strength.

In fact many if the world's best performing companies are a kind of exercise in socialism since the RSU programs share ownership and results of the company to the workers (even if it's a small share)