I know multiple large companies that would have no choice but to block any public use of these, as they have databases where these addresses have special meaning.
Yes, obviously that was a terrible choice to make. But it's there. And legal compliance means they can't just let these addresses in as normal unicast.
So while these can work as rfc1918 and similar, nobody will ever want to use these on publicly facing clients or servers. Too many places will never support them.
Plus there's tons of legacy equipment that simply won't work with 240/4. It will be a support nightmare. Arguably, opening up 240/4 could've been done around the time we started rolling out IPv6... It's a bit late now.
Yes, obviously that was a terrible choice to make. But it's there. And legal compliance means they can't just let these addresses in as normal unicast.
So while these can work as rfc1918 and similar, nobody will ever want to use these on publicly facing clients or servers. Too many places will never support them.
I'd rather be behind 3 layers of CGNAT.