Frankly, it also might be useful for how to properly do a charismatic mass...
And to be fair, a partial score for the Protestants: The earliest bible to include the verse, "For thine is the kingdom, and the power and the glory, now and forever," is from the ninth century. While the Didache does not contain this in the entirety, it does include a substantial portion, "For thine is the power and the glory" after the Our Father.
(The Catholic church does not include this at the end of every recitation of the "Our Father," (Lord's Prayer); it is considered a pious addition, but nonetheless an addition to sacred scripture.)
I'm a Protestant, and I've experienced the pain of being the only person still standing and talking in a church when the Catholics came to a screeching halt at "deliver us from evil" and I kept going. And the worst part was, I had (for reasons too involved to go into here) worn jeans and a Detroit Lions jersey. Four hundred people in suits and dresses looking at the dipstick Protestant who's standing up with Barry Sanders number on his back. Not a stellar moment in church history.