> I entirely disagree. Due to a combination of ISPs sticking with what they know and refusing to update... and vendors minimising their workloads/risk exposure and only updating what they "have to"...

You misunderstand me, though the misunderstanding is quite understandable given how I phrased some of the things.

I expect the updating usually occurs when buying new kit, rather than on kit that's deployed... and that that purchasing happens regularly, but infrequently. I'm a very, very big proponent of "If it's working fine, don't update its software load unless it fixes a security issue that's actually a concern.". New software often brings new trouble, and that's why cautious folks do extensive validation of new software.

My commentary presupposed that

  [Y]ou're adding support for a new Internet address protocol that's widely agreed to be *the* new one

which I'd say counts as something that a vendor "has to" implement.

> I think it's much easier to update consumer edge equipment. The ISP dictates all aspects of this relationship...

I expect enough people don't use the ISP-rented equipment that it's -in aggregate- actually not much easier to update edge equipment. That's what I was trying to get at with talking about "ISP-provided routers & etc are crap and not worth the expense".