I can see both sides. If your PHP app depends on non-core modules, or resources that might clash with more than one instance running (apcu comes to mind, or redis), or a complex database layer, etc...maybe docker would help.
But there's a bigger issue here. The comments the OP received, are heavily worded to the point that they explicitly state that the article made them angry.
Regardless of whether containers are suitable or not for task X or Y, it is very difficult to have a normal conversation, if one's comments can actually make people angry.