They can only send the marketing emails if you have the "send me marketing emails" checkbox checked when you type in your email address. Dark pattern, yeah.
That has never stopped companies from spamming me with marketing even when I didn't agree or even explicitly disagreed (unchecked). Not a single company has been or ever will be held accountable so they just keep doing it.
Isn't the email at the top of the form and the marketing checkbox at the bottom? It's an awful dark pattern and makes me want to not use any company that uses shopify.
They require your full address to show you shipping prices as well (vs just letting you estimate with country and postal code alone), so I have to punch in a ton of details before I nope out at awful shipping costs, and I end up with these emails.