Very broadly speaking, there are two categories of website owners--those who host their sites themselves (whether on their own hardware on-premise, or on a hosted server somewhere that they have full control over), and those who use a hosting service. For the former group, installing and setting up a client to obtain and renew a cert really shouldn't take more than about 10 minutes, and once you're done, you really shouldn't need to mess with it again. For the latter group, the expectation is that they'll use a hosting service that directly supports Let's Encrypt. In that case, obtaining/installing/renewing the cert is a matter of checking a box or pushing a button on the web control panel (if that much--some hosts even enable everything by default), and you're done.
If you're using a hosting service for your site, and your host doesn't directly support Let's Encrypt, you really are probably better off using either a different CA or a different hosting service (or, I guess, just giving up on security for you and your users), as Let's Encrypt just isn't designed to cater to that use case. It doesn't actively preclude it, but it doesn't really do much (if anything) to enable it either.
It never ceases to amaze me how people continue to come here to complain that Let's Encrypt isn't very good at doing something it was never intended to do in the first place, rather than complain to their user-hostile hosting providers.