Once upon a time there were a number of large European airlines that had surplus sim availability. They dreamed of a time when they could grab a cadet that had jumped through all of their entrance tests and put them through a tailored course that was relevant to their operation. Hence the MPL was born.
Unfortunately the regulators didn't limit the course to only the airlines that had jobs available. Instead opportunistic TRTO's cottoned onto this and started to offer courses as well.
The most obvious difference to me about the MPL (or how it was supposed to work anyway) is that you have passed an airlines entry tests before embarking on the courses. Compare that with the traditional method of throwing lots of dosh at your courses and then sending out a 100 cv's wondering why no one ever calls you. Its a process of self selection and sadly there are many people that will NEVER EVER get near a commercial aircraft no matter how hard they try and how much money they throw at it.