The problems is that many popular hosts have not deployed PHP 5.3 yet. So, if you're planning on using this framework, you need to make sure your host and anyone you distribute it to are using at least 5.3. This nullifies one of the common reasons for using PHP ("it's supported everywhere").
That just means the situation changing as time goes on, not anything about a myth. Of course at some point everyone will be running >=5.3, but I still hear about PHP 4 after all...
