Ok let's look at it this way. Yoda says he has trained Jedi for over 800 years. We can't assume he was brought in as a baby like in the Prequels, because we don't know. We have to assume he was probably a Jedi for a while if he was able to train Jedi. So Yoda has been a Jedi for over 800 years. Obi Wan had been a Jedi for something like 25 years; his entire life. Both of them have been Jedi for all or most of their lives. So Luke is the last Jedi left. Yoda tells him to pass on what he has learned. Does it make sense that Yoda means "Train your sister" or "Train more Jedi"? I'd say the above points to the latter. Yeah the Jedi became corrupt, but the entire organization and their ideals weren't bad. I really doubt that Yoda meant "**** it! Just pass it on to whoever you want, like two people at most." I don't think you give over 800 years of your life to a group, have it destroyed, have the ability to rebuild it in some form, and then not care about rebuilding it.
As I and KhalDrogo have been trying to say, you're letting your knowledge of the prequels influence your perceived memory of the OT.
I guess I come at this argument from a much different perspective from you - I don't count the prequels as canon. I dismiss them entirely.
So I'm just going by what was said in the 3 original movies.
And in the original 3 movies, the only inkling we had as to what jedi training was like were the few days Luke spent with Yoda on Dagobah.
Did Yoda train jedi one at a time? In pairs? In classes of 30, or by the hundreds? We don't know. It's never said.
Did Obi Wan begin his training as a toddler? We don't know. It's never said.
Was there a Jedi Academy, where Jedi Knights were churned out by the thousands? It's never said.
Was there a Jedi council? Were the Jedi the police of the galaxy? Did the Jedi fade away because of corruption within?
None of those things are even
alluded to in the original trilogy.
Edit:
Also, while I'm ranting, the whole notion of taking children from their parents and putting weapons in their hands and teaching them combat skills when they should be playing and learning and discovering the world is effing FASCIST, and goes against
everything we were taught the force was in the first 3 movies.
The force was spiritual - it was Taoism, in space. Luke was the Yin, Darth Vader was the Yang.
"Using the force" was meditating - achieving a sense of "oneness" with the universe.
It's unfortunate that old George quit smoking pot and forgot what the hell he was on about when he sat down to write the prequels.