It's not so much the degree of difficulty, but rather that the difficulty exists in the first place.

The PHP experience is absolutely horrible compared to those of Java, Python, the .NET languages, and even to those of C, C++ and Objective-C.

Take Java, for example. Debugging works seamlessly in pretty much every major Java IDE, including the free ones, on pretty much every platform used for Java development. This has been the case for a decade now, if not longer. It takes basically no effort to start debugging Java code.

The .NET experience is even better, although more limited in terms of tooling. Debugging is stupidly simple and very efficient when using C# and Visual Studio. Again, it has been like this for many years now.

PHP needs to get its act together so that debugging is at least as simple as it is when using those other languages and runtimes. Anything less is just plain unacceptable today.