>>42903733>>42904096Two reasons
1. A shitty way to explain shit like Kangaskhan, Porgon, etc. breeding
2. When breeding was first introduced in Gen 2 it was treated as a new thing. In older Pokemon lore the Pokemon were only a recent appearance, new Pokemon were genuinely new and largely unknown, so the idea of Pokemon breeding being a mystery wasn't a stretch, and it let them showcase baby mons. After the old lore was largely thrown out and Pokemon always existed on Earth, they didn't bother changing this, so they just pretend that instead it's some grandiose mystery, but the context to why it was a mystery in the first place is gone, making it silly.