What are these other alternatives? Just saying there are others over and over is meaningless unless you actually articulate them.
What harm does water do to concrete? It can damage the concrete, causing spalling and in the most extreme cases it can corrode the steel reinforcing (rebar) result in a structural failure. That though is rather irrelevant because nobody is talking about the concrete structure failing or being compromised. The panels were furred out from the primary concrete structure. That's what failed. Multiple anchors all being installed incorrectly and all lasting is a stretch. Water though over time would corrode those attachments and when impacted would take down multiple pieces together. Water intruding into a building envelope and corroding the interior is a regular enough occurrence in Florida, it's not some far fetched scenario. If anything, it is the simplest explanation for the extent of damage.
Photos tell a lot. Nobody assessing the situation is able to go back in time and watch the failure occur. They're dependent on looking at the aftermath, not much different than what we see. There are photos available of the site before more of the facade was removed, showing how the panels were not directly attached to the concrete itself.