The other CAs aren't prohibitively priced for anyone who has a business need for lots of certificates, in case Let's Encrypt disappears or goes rogue.
Not if you look at the per-cert pricing, but if you factor in the cost of "dealing with incompetent sales" and "convincing accounting to keep the contract going", they absolutely are.
> If you have a server or other device that requires automatic issuance of certificates and supports the ACME protocol, you can use our free 90-day ACME certificates on all plans.
Zerossl is integrated with Caddy by default and there’s no indication from Caddy that you would only be able to renew the cert twice before needing to cough up some money.