Why need Frameworks?

I dont know why people "force" so much on frameworks. I am just not able to understand.

I know I may be talking like a fool but then if you only want to write better code, you can even write it in Object Oriented way right?

And I dont mean nor I want to say that people who write/use frameworks are fools. But I dont.

So may be I am a fool.

I am going to stick only with PHP, MySQL and Ajax for development and lets see if it can work out for me.