1. The develop-try cycle is fast: In PHP if you change some code it will be immediately visible - no server reload needed. That's because the "application" is reloaded at every web request. There is no application server.

2. The PHP ecosystem is quite mature, and packages are of good quality in general

3. Dependency management works well. You will rarely end up in a state where your dependencies are incompatible between each other (something that happen often with npm for instance)

4. It's faster than python/perl/ruby