> Because TCP/IP is used for more than just the internet.

So I'm so stupid & ignorant of security I think I would define "Internet tcp/ip" which conformant stacks block this rubbish by default like they do any other non-conforming packet. Thus reducing the attack surface essentially with no tradeoff. Weird uses can use customised lwip or whatever for these uses where we don't know the who, the what or the why (or perhaps even the IF).

Seems like nobody is shipping these firewall rules by default on internet routers. We get the vulnerability and as a tradeoff we get nothing of any value to us. Who do we thank for that?

What is the rationale, the justification for not paring away the garbage that does nothing but create vulnerabilities?