Yeah, I think this is bad advice. One of PHP's drawbacks is that it is such a loose language. If you don't use a framework, you will most likely fall into the trap that many PHP coders fall into, which is being quite lax with your code and consistency.
Using a framework really helps you maintain some consistency throughout your code. If you don't like what other people have made, build your own.
Really? While I agree that a lot of frameworks are a bit on the heavy side I wouldn't advocate against using one. Frameworks do have something to offer that stock PHP doesn't, structure. I can't imagine going back to doing PHP without so much as my little 300 line MVC wrapper to work in. It's certainly possible to write good PHP without any sort of a framework, but it's infinitely easier to write really bad PHP that way too.
As someone who has been called in several times to support existing custom-built PHP sites, I very much disagree. A framework will at a the very least ensure a clean organization. PHP is extraordinarily easy to make a mess of, frameworks help.
I'll have to say I disagree as well-- PHP with a good framework is a better language, hands-down. I don't enjoy coding raw PHP. Almost all of the frameworks are open source, and none of them forbid you from using raw PHP when you need to do so.
So the net recommendation is, get a framework that makes a lot of secure/clean decisions for you and diverge when you think they're reinventing the wheel too much.
OK, maybe not exactly, but many of them suffer from second system syndrome where they try to re-implement everything php offers.
Just use php directly.