Why PHP4?

Its because PHP got really famous with version 4.0 and many people actually
converted their CGI or other websites in to PHP 4 websites because it was
easy and cheap. But 5.0 brought too many changes like serious PS and
register global concepts for security, which is useful but made transition
difficult. I feel thats why PHP 4 is still supported.

Its not only the language that has changed, but also people had to upgrade
their skill set and there was some learning curve involved.

Unfortunately everyone fell in the trap of register globals which was not
dealt until php 4.3.1 as a security concept. Pear and Pecl were there but
everyone was pretty much writing all the code (reinventing the wheel) from
scratch. This brings in huge code base to change.

I liked PHP because intitially it was a procedural langauge and it resembled
C. But now with PS you can build powerful websites which is good.

There are many other cases but I feel strongly this is what makes them
still support PHP 4.

Thanks