Yeah, I was actually talking with Chad about this, in a different thread, just a few days ago.
Without front wheel support, you are, in fact, simulating a decline. If you have a weaker core (like me) that means your arms are taking more weight, and that could lead to overuse, soreness, and eventually pain.
I’ve got the wheel block on a book, right now, for an overall incline of 1" and might add more. Hadn’t considered not using the wheel block in order to move the handlebars.