Why do Legendaries have "Egg Steps" if they cannot breed?

Question

Don't understand.

Answer 1

Just like Reshiram,Zekrom,and Victini have Shiny Forms, but they cant be obtained. It was put there by Game Freak for who knows why.

Comments

Landorus,Thundurus and Tornadus can't breed, only Manaphy can.

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no you can't...

Answer 2

It's because if you hack or glitch, and get a legendary Pokemon egg, but if they don't have egg steps, your game can become ruined.
Makng "exceptions" in the system can cause those things to happen.

Comments

I don't think that's the right answer, plus, you don't have a source.

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http://pokemondb.net/pokebase/77199/why-do-pokemon-that-cant-hatched-from-egg-have-base-egg-cycles
It is there to keep the game from messing up.