For the spoiler, it kinda is: If you use a normal pencil and sharpen it every time it gets dull, about 90-99% of the graphite ends up in the trash. Even if you only sharpen when all exposed graphite is used, you'll be wasting 66%.
Mechanical pencils massively reduce this waste. Of course for arts etc. there are reasons to use normal pencils, but for writing it's wasteful.