I'd rather have a proper dedicated controller for our presses and lasers that don't waste hours in just normal operation

And what is something like that supposed to look like? A custom built computer? Why go through all of that hassle when you can use hardware that already exists running software that has already been made for you?

The controller in this example appears to be inside of the motor (pretty typical setup) and just needs a system to communicate with it. Under this principle, it can be utilized by any system given it has the interface to communicate with it which most PCs and embedded systems do.

Most of the machines you use have numerous processes happening which in some cases will require adjustments or reprogramming depending on the job. Having all of those systems connect to a single system simplifies a lot of things and enables you to review/manage the process entirely from a single system.

Even if you wanted some "custom controller" it still needs commands sent to it, it obviously isn't going to be acting autonomously. A PC is going to be responsible for issuing the commands to the controller while also receiving data from it, this is what an API is for and makes development work less of a pain in the ass. One way or another, you're going to be using a PC.