Time and causality doesn't work in a linear fashion in the warp. I'd argue that both explanations of the birth of a soul could be true. I'd argue that it would still draw its power from the warp (conservation of energy being a fundamental law that even the warp works within).
Either way, the Eldar will have been designed with a reproduction cycle that takes into account reincarnation. Without reincarnation, the Eldar population cannot reproduce as fast as it could pre-Fall.
The result would be the same. Not necessarily fewer Eldar births, but definitely fewer viable ones.
Do Tyranids have no soul? I'd argue that they do. Their constant psychic chattering creates the shadow in the warp. Without a soul, they would have no method of interacting with the immaterium on a biological level.
Turnip Jedi wrote:Doesn't help the Eldar reproductive cycle is one of the stupidest ideas in
40k which in itself is very Eldar, even our worst ideas are better than your worst ideas
...
Hah
I'd also point out that the most information we have about the Eldar's reproductive cycle comes from an in-universe Imperial perspective who could very well have got it completely wrong. Remember, everything you hear in
40k canon is suspect to propaganda, misinformation and ignorance