It's one of those tools that's in a weird niche. If you need to use it you probably shouldn't be exposing services to the internet. If you're trying to learn it's not going to teach you much. If you don't need it you won't use it anyway.
I gotta say, upon closer inspection Yunohost looks way more elegant and complete a solution than I was picturing. Figured it'd mostly be premade apps ready to install but there's also built-in LDAP + email, let's encrypt certificates, integrated security features, the list goes on and on. If the execution is even remotely as smooth as the documentation suggests, Yunohost sounds great!