A foil card has the same rarity as its non-foil version (e.g., a "foil rare")
In a late game top deck situation this is pretty bad compared to most other draw effects which is a fair payoff for a card that is exceptional when suspended early and cheap enough not to hamper curving out
Of course, it was the best efficiency in that deck, and the other decks were 1/3 of the probability of mass draws, even if they failed, it was possible to accumulate Chaos Soldier -Dog Wall -Dragon Cemetery, so it was almost three cards except for the deck that had no money to get this card
Its a paradox we collectors live with every day, a promise that secured the games past, but now holds its future in a very complicated, very expensive grip.
However, since "Dark Simorgh" doesn't require LIGHT monsters, these can actually slow down the summoning of "Simorgh" if used in large quantities (so you should minimize the number of "Lightsworns" used)