You're right about what the 4th amendment really says, and it's so spectacularly inane that I would never believe that educated adults could be fooled if I hadn't seen it personally. It really does just say "the government cannot search you unless the government deems the search reasonable or the government writes a piece of paper saying that it can conduct a search." And people sincerely think that is in any way a protection of rights.
If you view the government as a single entity, then the whole concept is irrelevant since it can amend, or even simply ignore the constitution as whole.
As far as I understand it, the idea is that due to the separation of powers, the people who judge whether a particular search is reasonable are not the same who create and implement them, so yes, there is in theory some protection of rights.
