>>35933885Because they went extinct. The dinosaur it's based on died along with its entire evolutionary line. There are no animals that come from it because they all died and their ability to fly was very bad (the Poké Dex even states that Archeops is better running than flying.)
Fossil Pokémon are doomed to be shit either intentionally or unintentionally. Maybe some day we'll get complete Fossil Pokémon without the rock typing and a stat boost. Maybe that day I'll be able to use my bro, Armaldo, in competitive.
A man can dream...