I also agree with Shopify. I need to know a lot more information than Mailchimp "allows". Knowing information about my customers will help me in choosing the proper demographics in my marketing and keep me from just throwing "stuff" against the wall to see what sticks. That data is priceless and I as the owner of my company MUST have access to it.
Here is what the popular Shopify Theme company OutOfTheSandbox recommends as Mailchimp alternatives. https://outofthesandbox.com/blogs/shopify-theme-blog/finding-the-right-email-marketing-platform-for-...