Well, it depends on how one interprets those events and then whether they are honestly presented to support one's arguments, doesn't it?
You frame Ho Chi Minh as one worthy of U.S. support in the 50's, and that to withhold such support was "one of many mistakes made by the U.S."
I haven't thought about him in recent decades but a quick glance reminds he was educated as a young man in the USSR during the 1920's and was sponsored-employed by its Comintern (which, when under Lenin, was just as ruthless as ever). He was always a dedicated communist and always disposed of his political enemies quite ruthlessly.
Are you surprised the U.S. ignored his overtures in the mid 40's given what it knew about him and after witnessing the USSR's behavior in the same time period?
Finally, the Dem-led Congress in the 70's wasn't just "power-drunk" as you suggest, they were also leftists; see for instance, the history of Kamla Harris and Dem Congressman "Red" Dellums.
Have a nice day.
I believe the OSS working with Ho Chi Minh knew quite well who he was.
And as far as the US supporting those that “disposed of their political enemies quite ruthlessly”... that list would be pretty long and comprehensive, in just the 20th century alone. South VN pols were on that list too, as I recall.
And they were power-drunk, after having taken out a sitting president, and taking on the CIA with the Church Committee just before the final assault in ‘75. As far as the leftists labels - well, duh.