The problem is that finding a root source of trust aren't easy this days. LE was neutral, now nobody is.

Russian government issued their new root certificate years ago.

Nobody trusted it enough to request a certificate from them or install it on their computers. Including almost all of the russian residents.

If Let's Encrypt enforces the rules, as written in pdf, a lot of people would lose a choice.

Frankly, even publishing a statement like that would make the scales of trust tip for some.