It has 1.3k layers, and this is for one component. Most design systems have around 50 components, many more complex than just a button. This is from the Ant Design System: https://www.figma.com/community/file/831698976089873405
Another way to think of it that may help put it into perspective for devs, think of the number of html elements in your average storybook page. Atlassian's page for their button has around 2k html elements to display all the variants and documentation: https://atlassian.design/components/button/examples. A Figma file represents all of the components in the same file, which quickly leads to an explosion of layering. Performance becomes a concern VERY quick.
In Photoshop a layer could have many shapes on it, if you drew one shape/mark on top of another within one layer, they would be inseparable. If you drew any two things in Sketch, they would always be separate, I suspect this is why they stuck with the term "Layer" even though something like "Object" may have been more accurate.
In sketch, instead of sheets of paper that match the size of the document, you have a perfectly cutout shape for each stroke you draw. You can then move that cutout around within the document.
Both of those have the same principle except one is cutout one is not.
When each layer is a transparent sheet it has an absolute Z order that translates 1-1 with the physical thing it’s virtualizing (transparencies, probably from traditional animation).
However if you cut out tiny shapes and arrange them with some on top of others to make a larger composition, there is no longer an absolute Z order to any element because there are a bunch of smaller stacks of various heights.
The virtualization no longer translates to the physical world, and from my experience that disconnect can sour people against a new way of doing things, regardless of whether it’s better.
https://www.figma.com/blog/building-a-professional-design-to...