[tedivm]

This to me is a server side issue- but that doesn't necessarily mean it's on the app developer. The behavior you're talking about can be set most servers directly, by adding the "X-Frame-Options" header into every request by default. Then exceptions would have to be made explicitly, by either the server admin or application developer. If anyone should change the default behavior (which I am not convinced is the case) it should be the server developers, not the browsers.

[eurleif]

X-Frame-Options only prevents the page from being displayed in a frame. It doesn't prevent a page on another domain from submitting a POST request.

[tedivm]

CSRF is solved very simply by using tokens for each field. If the attacking site can't load the other page, it can't pull the token out, and without the token the post gets discarded. If you've abstracted your form generation this should be super simple to add.

[divtxt]

Thank you for pointing me to X-Frame-Origin!

So, in the context of this discussion, why don't the browsers make X-Frame-Origin: DENY the default behavior?????