> webserver doesnt support business logic
Thats not a generic statement. It does when your server side logic is written entirely is PHP. AFAIK, there is no app server for PHP, though I admit my understanding of PHP even fails me. Also when you have a small scale project, using a web container gets the job done. Low complexity projects seldom require the power of an Application server.
Also, at least as far as apache is concerned, there is no reason why the Web Server can't have business logic. I know someone who has written an entire web site (not page) (and a complex one at that) as an Apache module. Very fast, but I, myself, would not want to be the one that had to maintain it (although there was flexible content).