That is an entirely unnecessary and quite a disparaging remark. Just because it doesn't meet your expected model of the world does not mean to insult those of us who have put a lot of time and effort in creating this project you get to use for free.
Node-RED did not start out as a general purpose IDE where you frequently switch between different files. It only runs the flows you have deployed. So the most typical use is to create one set of flows and have them run. When you switch to another set of flow files then the previous ones are no longer running. That is just a different model to your desktop word processor where you edit multiple files and can freely switch between them.
The projects feature was introduced to provide a better user experience for people who do want a more natural way to switch between what is being worked on. But with limited contributions from the community, the feature has somewhat languished and not yet made it to being on by default. That's still my goal, but there's a lot of work to do it get to that point.
On the main index page of the user guide there are 10 links to sections under "Using Node-RED", with "projects" in that list. I'm not claiming our docs are perfect by any means, but we do try to highlight these things.
Anyway, I'm sorry it isn't meeting your expectations, but I kindly ask you don't resort to insults.