You're right, that's the whole point - the commonly accepted (pre-GDPR) practice conflates these two things; and GDPR now requires them to be separated, which is a major change both in practice and in attitude.

You can have "take it or leave it" agreements, and you can have consent, but these are two separate things; it's not possible to obtain consent by putting some words in a "take it or leave it" standard agreement.