Kinda wrong.
Procedural generation isn't just throwing things together without rules. The more defined the rules are, the better the result.
You can take 5 different animals and randomly mix and match heads to bodies. Or, you can say the body of a zebra should not be allowed to have the head of a cat.
The latter constitutes a rule. The more refined the rule, the more targeted of a result.
Now we must also understand the universe is the SAME for every player. It's not unique. The same seeds are used globally which is why you can see the same planets others have visited.
The only real reason they chose generation is so they didn't have to model every planet by hand. This way you can have a virtual limitless amount of planets without needing to create them and a small package size. No building, tree, rock, etc is made from scratch by the engine. They make these assets ahead of time and can randomize the layout of a building or dungeon (think Diablo) or randomize the geometry of the rock, the amount of leaves on a tree, etc. Think of them as Legos.
The rules could have been more refined, easily.
There's a million ways to make procedural generation and you don't have to be a programmer to make the rules that the generation is governed by. You just need a bit of forward thinking so you don't wind up with a human head on a rhino's body with worms as arms unless that's what you are going for.