PHP (and JavaScript for that matter) historically did not have a good implementation of OOP, nor a culture around it. As far as I know, things have changed on that front, but it certainly does not surprise me that you were able to deliver a PHP product without touching it.
Doesn't mean that you're dumb or that other people lost their minds. My guess is you haven't given it a serious go, which is fine if you don't have a need for it. I personally find OOP fantastic for large codebases with multiple people working on them. Makes code a lot more maintainable and easier to reason about. The downside is that folks without a strong sense of architecture can get carried away with enterprise patterns and end up with abstractions on top of unnecessary abstractions. The basic tenets of OOP should be easy to understand if you just spend some time on it, though benefits can be hard to see if you haven't experienced procedural spaghetti code.