I wrote the linked article. I don't care what secure messenger you use. But if you choose encrypted email over Signal because "centralization", you're LARPing. The first criteria for a secure messenger has to be that it is plausibly secure, and email isn't. You'd use encrypted email (for "decentralization") because you understand the cost of losing the plaintext of your message is nil. If you tell strangers to do that, without certainty that their messages are also valueless, you're committing malpractice.