This is genuinely not obvious to me. What convinced you of this? Or, what do you think the world would look like if there were people who actually had a strong, reasonable, non-insane suspicion that they could do the things that cryonics people claim to be able to? To me, it looks like we are living in that world. Have you e.g. looked through the information, studies, and arguments on the Alcor website?
Well, you don't want to read the article I linked. Why would I want to read a bunch of studies published by someone with an obvious vested interest in convincing me cryogenics is not nonsense?