There's no such limitation with a dedicated webcam, the kind you mount on top of your monitor. Yet these also are noticeably worse than what you'd find in a 5-year-old phone.
Resolution is just one factor. What processing you do to an image can easily make a lower resolution image look better than a high resolution image with horrible colors, bad contrast, poor tone curves etc. I'd describe the output on Macs as "unoffensive". It isn't great, but it also isn't bad.
Most people who dabble in photography and shoot raw will have some idea of this. The (untreated) images that come out of my professional DSLR don't look as pleasant as those that come out of my iPhone. Even if they have 4 times the pixels, and each pixel has much more dynamic range. How the raw sensor input is interpreted, influenced by intent, and then rendered, can be the difference between something you would hang on your wall and something you'd delete.
I have half a dozen macs with cameras, including the 16" notched M1 Mac Pro. None of them produce a great image, but they won't stand out as bad in a video conference. My $1000 camera does stand out because of its poor image processing, especially in low light conditions. It is a bit sharper, but the colors look distinctly off.