To be honest, I’m not sure if it even exists.
It’s true that some writers are terrible. Some writings are best kept private. Lazy writing, mediocre writing, timid writing, lowest common denominator writing, rushed writing, uninspired writing, and so on and so forth are all examples of poor writing.
To what extent, though, are any of those unnecessary?
Any of the above examples can serve as a springboard for your next best piece of writing.
So if none of the previous cases is a waste, then none is an excuse not to write.
Just keep writing; at first, it might not be very motivating, but you can work your way up from awful writing to better writing, and if you keep at it, you will eventually get to the point where you can produce good writing.
Keep going, or more accurately, keep writing.