He didn't say you _can't_ use PHP for such things, he said PHP is "great" for getting smaller sites built quickly. It's possible to build very large apps with P

He didn't say you _can't_ use PHP for such things, he said PHP is "great" for getting smaller sites built quickly. It's possible to build very large apps with PHP alone, if you like, but there are other solutions I think are preferable. Most of them weren't even available when Facebook was born. For example, I would rather build a Facebook-sized app in Rails than a PHP framework, especially with Rails 3's new features. There are some very capable PHP frameworks out there, but you'll still end up writing much larger models and a lot more code than if you were using Rails.