There's a lot of wiggle room. Sometimes a font designer will even throw in a single serif because hey--this is also an emotive art. Or maybe for a specific reason due to the project spec.
When I used to teach typography in the 2000s, sometimes students would point this out. Or as an example of a beginner's lesson, they'd use a font without really examining it, and some detail about the font would catch them out later.
It's weird but most people pick fonts without really thinking about the font itself, or even reading its name, let alone examining it. They are thinking about their design, their thoughts & feelings, their message, their amazing design opportunity, or whatever.
Skilled designers need to be trained to think about whether they're basically hallucinating the purpose of the font, as a few seconds of inspection will often make the original purpose really obvious. To people who learn how this works, it becomes just that obvious why those slab serifs might be in there.
When I used to teach typography in the 2000s, sometimes students would point this out. Or as an example of a beginner's lesson, they'd use a font without really examining it, and some detail about the font would catch them out later.
It's weird but most people pick fonts without really thinking about the font itself, or even reading its name, let alone examining it. They are thinking about their design, their thoughts & feelings, their message, their amazing design opportunity, or whatever.
Skilled designers need to be trained to think about whether they're basically hallucinating the purpose of the font, as a few seconds of inspection will often make the original purpose really obvious. To people who learn how this works, it becomes just that obvious why those slab serifs might be in there.