It locks content behind exploration of other content.
If you want to look at Minecraft as a level editor/creation tool, the content that allows you to create different colored blocks for example is contingent upon you finding some sheep you can lure to the right area, start them breeding with each other, find plants that can be used to make every kind of dye, dye the sheep's wool, make shears and shear them etc.
It could indeed take days to get set up for this, to make one giant work of pixel art for example.
Terraria is a game with even more unique things locked behind your progress, tons of tools you don't have access to until you beat multiple bosses and get to hard mode, and then adjust to the new difficulty of hard mode, learn to survive, and scour the world for chests that might contain the objects that let you make a more interesting world. It took me and my friends like a week to get to some of the game's elements.
But these are not primarily level editors, I think. They're games that you're playing. Mario Maker doesn't force you to collect rocks so you can place them in your level.