Accusing people of "trolling" when they explain why you're wrong is poor form.
The general idea you had was fine, there are indeed applications which necessarily involve side effects and the lambda calculus doesn't have side effects. But answering individual HTTP requests (remember PHP isn't a web server, it doesn't need to care about the details of how those requests are made, where they come from, or how answers are returned) isn't really one of those applications. Thus the lack of side effects isn't a deal breaker, and my explanation deliberately didn't use them.
All you need are some conventions. The same sort of conventions you'd need if you wanted to write pow() in the lambda calculus, or isalpha().
It's also fine that you didn't understand that, and needed to have it spelled out. The problem arises when you discover, oops, that you were wrong and rather than say "Ah, I see, that's not what I thought was going on" you insist that you're being trolled.