Im not saying its ghostproduction.
Im saying that labels and companies often pick up artists and in many cases that results in many people getting involved.
The hardcore examples are popmusicians, where they often dont write the music, nor the lyrics. They may sing, but even that gets heavily edited by other people.
Often they are just the face and a little voice, the rest is written and produced by other people.
The same thing applies to alan walker here, its not a secret to look up who was involved and he 100% didnt not "overhaul" his old version, it was different people and more people that added lyrics, vocals, post production and mixing.
Also: "they don't make them on their own but Garrix does, you can look it up if you want," Show me. I want to see garrix actually engineering his sounds from the very beginning. I HIGHLY doubt thats the case. There are very very few artists that actually do that.
*edit* To be clear: Im not saying that they COULDNT do it, Im sure they have some knowledge. Im more pointing to the fact, that often the starting point is a preset or they follow the normal rules of for example making "progressive house lead synth". Its not like all of that is creativity, its often just following already present ruls and making slight adjustments to your liking.