Diceware as a passphrase for online accounts

I’m reading about Diceware and cryptography in general and I know how secure Diceware can be. I stumble upon this part on The Intercept about Diceware and it says:

"You don’t so much need them for logging into a website or something else on the internet. In those situations, you get less benefit from using a high-entropy passphrase. Attackers will never be able to guess a trillion times per second if each guess requires communicating with a server on the internet. In some cases, attackers will own or take over the remote server — in which case they can grab the passphrase as soon you log in and send it, regardless of how strong or weak it is cryptographically."

So the question is, is it overkill to use Diceware on accounts like Facebook, Twitter, etc.? Should I rely on a password manager generating a random string of characters for these accounts and reserve my Diceware passphrase as a "master password" or a secret PGP key?