Arstechnica reports
In July of 2017, the nonprofit certificate authority Let's Encrypt promised to deliver something that would put secure websites and Web applications within reach of any Internet user: free "wildcard" certificates to enable secure HTTP connections for entire domains. Today, Let's Encrypt took that promised service live, in addition to a new version of the Automated Certificate Management Environment (ACME) protocol, an interface that can be used by a variety of client software packages to automate verification of certificate requests.
[....]Many hosting providers already support the registration of Let's Encrypt certificates to varying degrees. But Let's Encrypt's free certificate offering hasn't been snapped up by some larger hosting providers—such as GoDaddy—who also sell SSL certificates to their customers.
(Score: 1, Informative) by Anonymous Coward on Thursday March 15 2018, @09:23AM
You are mixing up his reasons.
Deploying official certificates (such as let's encrypt) needs to be manual, as the renewal requires an internet connection and the network is not connected to the internet. This makes the 90 day limit inconvenient.
Using an internal CA is inconvenient for different reasons.
Either way, buying an expensive three year certificate becomes the cheapest solution.