After years of constant updates and neverending new features, the modern desktop operating system has evolved into a slow, complex mess.
I hate this framing. The modern desktop OS, such as Linux, supports an ungodly amount of hardware configurations and devices and performs at breakneck speeds. Often with specific quirks implemented to work around hardware bugs. I wouldn't diss the "modern desktop operating system" when all this person managed to do is write an unusable toy replacement, no matter how technically difficult that is to do.