<aside> ℹ️ The whole point of the design is to separate the primary from the secondary. In other words: focus users' attention on the main thing to get to the action or find the information they need as quickly as possible.
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The essence of design is to highlight the primary and direct the user's focus on it.
Typography is part of the design, and it follows the same principles. We work with content and present it in an interface so that the user understands what is important on the screen at any given moment, how to find the main thing, and what needs attention right now.

Good typography differs from bad typography in that users instantly understand what is important on the screen and omit the secondary until they need more detail. To achieve this is a real art and the highest class of designer.

In user interfaces, the main things are headings, buttons, links, images, navigation, and controls. Secondary: text.
Sometimes text is primary in content-oriented interfaces, such as news sites, book reader apps, documentation, and long reads. And in that case, the text is really the most important thing; you have to put a lot of effort into it.
But in addition to content-oriented interfaces, there are countless other kinds of websites, applications, control panels, and different on-screen UI. The text has an auxiliary role in them, either a supplement to the main one or made for the robots. Unfortunately, the text in marketing sites is often for SEO, and no one reads it.

The text on the main page of stripe.com is definitely made for robots, with a separate link in almost every word. They know that no one will read the text, but without it, the design would not be complete.
We scan the headings, scroll quickly, look at the images, and sometimes look at the icons. Then we find a link or button and move on. It's the same with control panels: we scan the headings, look for the button with the desired action, and move on.
By understanding how users interact with the interface, we know how to create focus points so they can get what's important as easily and quickly as possible.