Why don't you enlighten us.
With the exception of rejecting papal primacy (and with it infallibility) and possibly the Deutero-Canonical books can you name a SINGLE doctrinal point upon which ALL Protestants disagree with Catholics?
And just so we're clear, by ALL Protestants I am including Lutherans and Anglicans. I've noticed, especially on FR that Evangelicals and Calvinists have developed an opinion that they somehow speak for the majority of Protestants and this belief is patently false.
Well, you've touched on two very important doctrinal items right there so I'll leave it at that.
My intent was not to get into arguing doctrine here; just pointing out that the person in the article really must address doctrine to be believed credible by most Protestants.