they are also for noobs that dont know how to read their plant
Surely this was joke, lol. Of course you should read your plants, but not having a meter makes it near impossible to diagnose, or better yet CATCH a problem before it start. If your not monitoring your run-off occasionally a problem can catch you off gaurd. If you have a problem you can't rule out over/underfed, because you have no reference point to begin with.
It doesn't matter what kind of meter you get. You just need something to use as a reference. Doesn't matter if it's .5 or .7 conversion, and no need to convert from ec to ppm. The meter gives the grower a reference, you should still be reading your plants. They are more for detecting changes in the growing medium before they become an issue.
I could grow without one, sure. I just like to catch problems before they start and monitor my growing medium so I avoid problems to begin with.