I already did and explained:
I meant "MSS Clamping"
If you don't limit to just ICMP - DHCPv4 Renewal on WAN is a major one you cannot just remove 
This is one example (the clamping) where IPv4 fails if it's not configured and needed. Another example is e.g. 6in4 tunnels, they expect ICMPv4 Echo Request IPv4 to work on WAN according to RFC - that would fail if these IPv4 rules were removed.
In any case, I'm also happy to help. Just let me know where the sentence would be good placed - and I don't mind either:
Wikis suggest imitating the LAN zone policy - if you set input rules to reject - I would surmise you know what you're doing and the consequences. I can also list things with IPv4 that would fail if you blocked input (e.g. IPv4 altogether if DHCP is blocked, also DNS resolution). Desprite being willing to add verbiage, I still don't understand how a user's improper firewall setting is the specific blame of IPv6 as opposed to the user who set it up. My only concern is that a potential Wiki reader will misunderstand the wording and unsfely open WAN. This is why I always offer to edit Wikis but ask the verbiage and location be supplied - when I don't understand the concept or reason for it.