Saying that something has been practiced for ages is no indication of it being correct. At the time of the writings of the Gospels it was being stated by the Apostles themselves that error was already creaping into the church. You gain nothing by way of authority by stating the age of a doctrine. You have to prove the doctrine. If you can't do that, nothing else matters.
For them, Catholic sacraments are out because they imply a spiritual reality grace being conveyed by means of matter.
When Jesus states that the flesh profits nothing re nourishment of the spirit, there is no dispute to be had. Flesh does not profit the spirit.
Torturing an argument is what has to be done on your side. The torture is the argument over the definition of the word "the", compounded by ignoring the fact that Jesus spoke in parables to unbelievers (even if they happened to be following him), further compounded by the fact that the Bread of life was eaten before Christ was ever born. The torture is that your clergy stumbled into something they didn't understand, then misconstrued it's meaning in their ignorance and started teaching it as gospel. That or they willingly got it wrong - which thoughts I'll not entertain.
Wrong they got it though and so it stands. It doesn't matter whether it's labeled Catholic doctrine, Protestant doctrine, Mormon etc. Scripture trumps doctrine. Not single verses but Scripture in context. One wonders why if consuming Christ's flesh was required, it wasn't evident in the OT when they were eating the bread of life. I keep returning to that because you guys ignore it as if to pretend that Christ coming somehow changed God's word. If God be the same yesterday today and forever, you have a real problem.