Basic step, once and for all.

I found this post. Basic steps
I had some discussions with new tango friends-of-friends about this (also beginners, like me). They told me about the Basic Step they'd learned. Honestly, I never heard of it before. Surprise, confusion. Then someone else entered the discussion. A wise and experienced dancer. No, you never ever step back -as a leader- in a crowded Milonga, UNLESS  you're dead sure there is nobody behind you. Makes sense.

So, Basic Step=No Good? But what about the classes where they do teach this?
And then all these YouTube video's, even from real (!) Argentinean dancers. They do it too, the Basic Step.

Who is right in this, and is there right or wrong in Tango in the first place?
Now I know, the question in itself is wrong.

When looking at the video's again I notice that these dancers are all alone on the floor. Showdancers, or they dance to show steps, their skills, whatever.

My conclusion? Basic step is allright, but do not do this at your local Milonga.