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.