That's why "SSL Everywhere" is security theater. To have "security" on pages that don't need to be secure requires weakening security on the pages that do.
Nah, you can still have separate secure domains with EV certs for taking credit cards. That way your customer's browsing habits and product preferences are protected from snooping by their ISP, the page assets are still cached and DDOS protected, and the credit card data is still sent to a separate domain without an intermediary.
The only thing still to worry about is your caching provider sending maliciously modified content that bypasses your secure domain.
That's the problem. If you only use SSL/TLS for security-critical pages where there's a login or a credit card, you don't need some massive cloud-based service to cache your stuff. Many sites still use "transferring to secure site for shopping cart checkout". That's fine. If you use SSL/TLS for everything, now you have a load problem on the secure infrastructure.
That's why "SSL Everywhere" is security theater. To have "security" on pages that don't need to be secure requires weakening security on the pages that do.