If I'm going to guess is that you have interacted with non-professional and/or beginner level PHP programmers, they could feel threatened becuase the only development skill they have is rudimentary PHP and you are asking them to replace that with something much more difficult. I have seen some of it myself, and it has always come down to lack of skill.
And this makes sense why you have encountered this within the larger PHP community, becuase PHP is an easy to learn beginner friendly language that is used by the majority of blog and forum systems, zero setup web frameworks, and all of it can be set into production on almost every server on earth. Thus there are many low skilled PHP developers, probably more than moth other languages.
And this is the lessons, it is important to understand that every community consist of large variety of disparate groups, especially within the PHP community, and it is up to you to learn to distinguish them. Unfortunately many are blind to this when it comes to the PHP community, outsiders may think the work I do professionally is the same as someone setting up blog for the first time, just because we use the same language. It would be same to think that the result of a first grader learning to write is the same thing as Tolkien's writings becuase both are in English.