It isn't the oven, it is the heat.
Sorry. That did not quite answer my question. Why go through the effort and expense of building an oven when you can get results (AKA The Heat) like that for under $400? Looks like the heat is there at a bargain price.
I can tell you my reasoning. First, all you can do is pizza in that tiny Blackstone oven and only one at a time. I enjoy the real wood experience. I need to be able to cook bread, some BBQ, Roasted Chickens at 600 degrees is so cool and other things. I love the Italian look of my oven and it is the best compromise for me. Also, in comparison with having one built for me, it was not expensive. There are cheaper SS ovens but the size, mass and heavy duty construction is quite satisfying. I just want others to know that the oven is not a joke. I know the prejudices here against it. And the prejudices seem to come from people who have little experience with them and assume that they are built like a toy.