Using non-private IP for your local network isn't "silly", it's just that we've grown accustomed to not doing so out of necessity. Reusing the same IP address for multiple hosts is problematic, even when there is an RFC that says it's okay to do so.
For instance, I've got a tinc VPN network setup between many of my hosts. What IP range should I set that to such that it will not clash with whatever access network my laptop roams onto? The proper IP-philosophy answer is to apply for a block, even if it's never announced by BGP.
The pragmatic hack is to attempt to choose the most obscure block that isn't likely to conflict with the public Internet or with how local networks are generally setup. In my case, I chose something NOT from RFC1918 (so shoot me).
It's of course less of a big deal if you do realm / split-horizon based routing. But that is not straightforward to setup, as it's getting away from how IP was designed to be used.
For instance, I've got a tinc VPN network setup between many of my hosts. What IP range should I set that to such that it will not clash with whatever access network my laptop roams onto? The proper IP-philosophy answer is to apply for a block, even if it's never announced by BGP.
The pragmatic hack is to attempt to choose the most obscure block that isn't likely to conflict with the public Internet or with how local networks are generally setup. In my case, I chose something NOT from RFC1918 (so shoot me).
It's of course less of a big deal if you do realm / split-horizon based routing. But that is not straightforward to setup, as it's getting away from how IP was designed to be used.