Well basically, you cd in the shell, and then it shows:
"direnv: loading ~/dev/foo/.envrc
direnv: export +DATABASE_URL"
Is this "implicit" to you ? Because to me it's pretty explicit. But yeah it's automatic, if you don't want this behavior, you don't install direnv. Just to be clear, implicit is "suggested but not communicated directly", and to me, this is communicated directly, so I don't see why it would be implicit...
From your description, direnv is implicit and noisy, whereas dotenv seems to be (unless you embed it in a script) explicit and quiet.