The reason is that it's a new house. The electrician was not thinking about the current needs only. Before you install wiring through all of the walls and for the outside walls, you make sure they'd be good for the current needs as well as future needs (at least as much as you can think of today) and hope for the best.
The new red Category 7 were also the best cables for external use.
only an inexperienced sparky would fail to consider the very well known interoperability / compatibility issues of cat7 physically connecting with cat5/5e/6... CPE, like today's IPC and everything else. I can't see future generations of IPC needing anything more then 100Mbps FDX anyway, even 8K / 12MP etc...
IMO Cat6 will be good for a very long time yet in many/most SOHO environments....and far more economical and easy/versatile to install