Nobody else thinks that the FCC decided to exclusively pull data from congested cities (I guess in order to intentionally fool theselves?), so they have no reason to look up the sampling method. You however do, so you should look it up, go through it, then give your evaluation of it.

When you make up an accusation from whole cloth, people are going to downvote it. They'll probably downvote even harder after you ask for other people to give you proof to refute the accusation that you made up from whole cloth. If you find the sampling method, and it turns out your suspicions were true, and then you write a comment explaining that, they'll give you hundreds of upvotes to offset these two or three well-deserved downvotes.