Was there some particular bright line at which cryonics flipped from "impossible given current technology" to "failure to have universal cryonics is a sign of an insane society"? That is a sign change, not just a change in magnitude.

If we go back 50 or 100 years, we should be at a point where then-present preservation techniques were clearly inadequate. Maybe vitrification was the bright line, I do not pretend that preserving brains is a specialty of mine. I just empathize with those who still doubt that the technology is good enough to fulfill its claims prior to seeing a brain revived. We have a bold history of technological claims that turned out to be not all that, but we promise that it will work fine in twenty years.

That seems like a perfectly sane outside view: every (?) previous human preservation technique was found inadequate over a span of a few years or decades, so we assume against the latest one until proven otherwise.

We must still have large areas of the planet where it is still sane not to sign up your kids, notably where the per capita income is below $300/year.