Oh, Great another person who thinks only they understand this is a fantasy game and thinks the rules of the world don't matter....
Perhaps you should pay a bit more attention to who Umbran his and the views he has posted on these forums before making such claims
...they should have a consistent world. If all races can inter breed where are the half-Gnome half-orcs?
Why? And more importantly, which world are you talking about? Others have tried to point out to you from the beginning of this thread that their is no one answer to these questions. D&D is NOT a single mythology. It is not a single world, it has no unified answer to history or why's.
Do you want to know about half-orc in the Forgotten Realms? Greyhawk, Dark Sun, Birthright?... Their are dozens of official D&D settings that have been published, each with its own legends and history and mythology. Each one has its own take on the questions you are asking. Why do you continue to assume their is only one answer?
They introduce that some races can hybridize so they should state why, when, and which ones.
Who is "they"? And why should they explain anything to you?
Do you know that their are hundreds if not thousands of people who have authored official content for D&D? That their is no single source of truth, no sage or authority who can say "This is how it always is". Numerous people have defined, officially, the origins of the different species in D&D. Each has done it with their own views, and often in different ways for different settings.
And, why should any of them have taken the time to answer these questions? Because you find them valuable? The lore is what it is. IT is often incomplete, jumbled, contradictory and nonsensical. Discuss your views, but demand some sort of official answer for something like this? That's, well, I won't say what I think that is other than useless.
If your here to imply that people are stupid for talking about D&D rules and mechanics of world building … please start your own thread. This thread is about which races can mix with which other races and why. If you don't want to talk about he topic other then to say the topic is stupid, don't post on a thread. If you actually have something constructive to say on the subject, the please post that with out the dismissive comments about the subject of the thread.
Yea, that's probably not the right attitude to address one of the forum moderators, even when they are posting as just member. Heck, it's certainly not a productive attitude to address anyone on the forums with.