Selfhosted

Edit: no, it doesn't. Looking at the comments below, it's public key crypto.

Original comment:

The problem is that if that is your threat model, then the VPS provider, ISP, and literally everything between you and letsencrypt can pull a conpromised key fro letsencrypt.

This actually happened btw, an xmpp server was attacked this way, they compromised not the server itself, but the VPS provider MITMed their traffic: https://www.devever.net/~hl/xmpp-incident

If your threat model involves this, then the only solution is Tor, which eliminates these requirements of trust.

Yep, that's what I described and any CA accepted by the client can do it

which is still there if you are not using lets encrypt, because they can strongarm them to make a fake cert for your domain, and install a proxy repackaging HTTPS traffic with the fake certificate. all browsers trust the lets encrypt root certificate, so they won't see anything suspicious.

the only thing there today to detect this (but not avoid) is certificate transparency logs. all modern certificates are required to be added to this log, for the CA to remain compliant. but browsers are not checking the logs, that would be a lot of additional traffic and how do they decide if a certificate was created maliciously? also, lets encrypt could afford being noncompliant, browser vendors can't realistically just distrust their root certificate, many sites would become inaccessible.

They don't have your private key

Yes, the private key never leaves your machine.

You send them a certificate signing request with your public key, they put their verification stamp on it and send it to you.

The only part they have to play is verifying that your certificate is trusted by a root certificate.

The CA cannot decypt: they don't have the secret key which only the server has. When requesting a new certificate from the CA, the server generated a secret key (aka private key) and then generated a derived public key that goes into a Certificate Signing Request (CSR). The CSR is what the CA receives, not the secret key, and then the CA returns the certificate file to the server, which has been endorsed by the CA and thus trusted by the user base.

Phrased another way, a certificate is the instrument that confirms that a purported public key can in-fact be safely used, and that no MITM attack is happening (assuming you trust the CA that signed the cert). But once you've confirmed the public key, the rest of the cryptography is public key cryptography, meaning the secrecy of the secret key is the whole game.

Usually they make money with extended certificates where they not only offer a certificate for example.com but also certify that it belongs to Example Ltd.

Those extended certificates used to show the company name next to address bars, but I don't think browsers do that anymore.

That would be just a nuisance until a new certificate is generated with another vendor (possibly not for free, but cheap enough).

And ICAAN can hand your domain over to US law enforcement regardless of the TLD and your register.

Is that also part of your decision tree?

I think you misunderstood something there; they're very explicitely offering free certs.

I just went 90% through the process (I might need them anyhow later this year), it's like this:
What you say is a PRO feature, unlimited certs with one account, is not meant as "unlimited in time" but "unlimited number of certs at any given time".