Which means
a) You're going to forget it at least once.
b) For every developer mindful of this, there will be hundreds not knowing about it.
If you ever put "you just need" into a sentence about security you've already lost.
If you ever put "you just need" into a sentence about security you've already lost.
Which is why you should never process raw input in multiple places in your app. One method I've used for over a decade of webdev in any language: there's only one place to get the input from, and that place requires you specify what input is allowed.
User input need to be sanitized always. Rails make it easy and is the default way.
Regardless, it's not a knock on rails. Just saying it's not necessarily a magic bullet to secure apps (and I don't believe rails nor PHP needs to be).
Edit: It's not actually a footnote -- it's actually just the only item on the lonesome "Security" page.