Exactly - which would likely be a persistent necessary cookie on most websites.

Cookies are very small snippets of code that have a specific purpose. Making a one-size-fits-all cookie would make them complicated and much harder to track - which goes against the point of a cookie. Also, cookies are often independent of each other because they are from different providers/different tools. Having a one-size-fits-all cookie would also present a security hazard and make laws similar to GDPR about cookie tracking difficult to implement. An example of a tool that actually does use one cookie is Adobe’s Marketo. You can read some more about them here. https://termly.io/resources/articles/types-of-internet-cookies/

As someone who works in tech, I can confidently say that many people plainly do not understand what cookies do and why they exist. There are plenty of cookies that are good and useful, but third party advertising tracking cookies are the devil folks don’t like. Necessary, performance and functional cookies are all chill.