Wouldn't a Redi-Mix Pyramid be easier?

Wouldn't it be easier to use a concrete mixture to build most of the Great Pyramid. Why would they do it the hard way?

Im in the construction business and trust me it's easier to pour a slab of concrete than to have it delivered, and we have heavy equipment at our disposal.

I ran across this video which proves the Pyramid builders were capable of making a redi-mix.

I guess they wanted to prove to future civilizations that they were capable of doing immense things and we shouldn't settle with crappy little huts in the future, as in if we could achieve this so can you.