Any reason to use a STAB move if it has no coverage?

Question

I always think its useless to give a Pokemon a STAB move that doesnt cover, but when I look into movesets, people actually do it. Here's an example:

A Moveset for crobat could be:

-Brave Bird
-Steel Wing
-U-Turn
-Cross Poison

I always think Cross Poison is useless, because brave bird works better for grass types, which is the only type poison is super effective against. (This is for 5th gen, so no fairies here). But people still seem to suggest cross poison. Why is that? Am I missing out on something?

Comments

There is no reason to use a STAB move if it has no use.Cross Poison is normally replaced by a better move in this case like Taunt

Answer 1

People are suggesting because it has critical hit and has the chance poisoning the foe.It also has stab.

Cross Poison deals damage and has an increased critical hit ratio. It has a 10% chance of poisoning the opponent.

Source

Comments

You also get a boost from STAB move too

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Cross poison is a pretty strong move and I would recommend it.