ISRG (Let's Encrypt's parent entity) wrote Certbot, initially under the name "letsencrypt" but it was quickly renamed to be less confusing, and re-homed to the EFF rather than ISRG itself.
So, what you've said is true today, but historically Certbot's origin is tied to Let's Encrypt, which makes sense because initially ACME isn't a standard protocol, it's designed to become a standard protocol but it is still under development and the only practical server implementations are both developed by ISRG / Let's Encrypt. RFC 8555 took years.
Yes, it started that way, but complaining about the current auto-update behavior of the software (not the ACME protocol), is completely unrelated to Let's Encrypt and is instead an arbitrary design decision by someone at EFF.
As far as I remember, since the beginning certbot/let's encrypt client was a piece of crap especially regarding the autodownload and autoupdate (alias autobreak) behavior.
And I couldn't praise enough acme.sh at the opposite that is simple, dependency less and reliable!
Honestly I abandoned acme.sh as it was largely not simple (it’s a giant ball of shell) and that has led to it not being reliable (e.g. silently changing the way you configure acme dns instance URLs, the vendor building their compatibility around an RCE, etc)