I believe this issue is pre-dated even further, back when iPod users didn't like that occasionally a random shuffle would play the same song back-to-back. So the 'random' shuffle was made a bit less random.
A shuffle already implies shuffling like a deck of cards, so you wouldn’t get duplicates unless you had two of the same card, and I that’s how it was described in the manual.
I can't think of why someone would prefer a truly random song being played from a playlist rather than the "deck of cards" method.
Probably doesn't go back further than that, unless jukeboxes has a random play option.
Suppose shuffling results in ordered set [b, a, c]
Suppose user plays through the entire set. Now it's shuffled again before repating.
Suppose the new shuffle results in ordered set [c, a, b]
The user now hears c play after c
2. Your claim is not even true as written.
3. I'm tempted to assume the user has a reasonable amount of music, so it will last as long as necessary. And you can't force me not to assume that.