I agree with you on this. There are not really any good arguments against God's existence simply because the nature of the debate is that the arguments come from those wishing to prove God exists. Just like, I guess, there aren't any arguments against the existence of unicorns or Santa Claus.That's pretty unrealistic
Especially since there are 10s of arguments for the existence of God in all their variations, and the number of arguments for atheism is basically "evil =(" which isn't actually an argument against God, and moreso against a specific rendition of God (and some others that no one argues for because they are pretty bad arguments)
A true agnostic would say though that the evidence presented for God's existence is perfectly countered by strong rebuttals against those arguments. It's easy to see then why someone would suggest that the two sides are roughly equally matched. Like you, though, I don't think it's a perfect match - we just differ on which side we go to and by how much