The biggest issues I see with the language didn't made into this list: for instance, I can think about more serious issues like accessing the wrong variable nam

The biggest issues I see with the language didn't made into this list: for instance, I can think about more serious issues like accessing the wrong variable name does not returning an error, assignment and initialization being the same (thus also suffering the same issues related to wrong names), various surprising type conversions, defaults, and so on. I guess it all boils down to the mindset of the language itself, as the article says. However, I disagree that "other languages do not work like that thus are not as easy to test". You can implement this in any way you like in any other language. You can implement your webserver by forking a new process at every call. You can even use a worker that communicates to a different hot-swappable process. It can efficient as you want - copying the whole data around, sending file descriptors, etc. The alternatives are endless. PHP may be "interpreted and hot-swappable" by default, but that's an accident from it's design and it only works like that - if you try to use it as a long-running process, you'll run into a lot of issues. It's also terribly inefficient - have you ever developed a web interface for an embedded platform? A really embedded one, like 32MB of memory, shared with the application itself? I guess in the end it boils down to the duct tape analogy: it's terribly fast to prototype something with duct tape and scraps and you can join a multitude of materials in a very simple way - just put everything in place and cover with enough tape to hold it together. Surely, it works.. but that's about it.