Because it is the TRUTH.
That is a poor excuse if I have ever heard one. Do you go up to overweight people and say "You're fat"? Or go to a nursing home and say "Don't worry you don't have long to live"? It may be the TRUTH but it is a poor example of which to do. Eph 2:9 and many other places in the Bible tells us not to boast. And that is what most of the Catholic threads are - boasting. Look at us!! We are the Church!! We have a superior church and are a superior people. Balaams donkey spoke the TRUTH but he was still a donkey. If the fact that boasting is abhorrent in Gods eyes does not deter you, I will pray for your soul.
Peace be to you