

So do that. You can do that with Signal.
Do you know of anyone doing it? Other people have said there are difficulties.
You wouldn’t register on websites, but you would communicate with them over plaintext. I hope that makes it clearer.
It is ok, in that era (dialup or wired internet) unencrypted http was basically as secure as unencrypted landlne phone calls. People still have unencrypted phone calls all the time. Typicalally sites would show public content (like product pages on an e-commerce site) by http, then switch to https for checkout to protect stuff like credit card numbers. Encrypting everything became important when wifi became widespread. Wifi hotspots would hijack DNS and spoof entire web sites to steal credentials. Also, LetsEncrypt made it possible to bypass the CA scam industry, making https-everywhere more popular. Public awareness also increased due to Snowden’s disclosures.
The RSA encryption patent also expired in 2000. Before that, US website operators were potentially exposed to hassle if they didn’t use a commercial server with an RSA license ($$$). But, it didn’t apply outside the US and FOSS SSL servers existed for those wanting them.
Hmm ok, though if a security program needs frequent updates, that’s a cause for concern in its own right… :/