Because it's fake. If you don't care about that and you're willing to bet your teeth on Chinese quality control then go right ahead. For how little weight you'd be saving I wouldn't bother, and if you're after the vibration damping that a carbon bar may offer you (no guarantees with that one, it could be stiff as fuck) then just get some cushty grips, some nice gloves, and man the fuck up.>>1120856
Either of those tools will suffice. Slide on your desired amount of spacers and the stem and then mark a line at the top of the stem and cut as close to that as you can, then when you install everything stick another spacer on top of the stem (everything should compress slightly as you preload the headset so the steerer will stick out past the stem slightly which is what you want).
Also make sure you have a carbon appropriate star nut, usually a reusable expanding bung that you secure with a hex key. This is assuming that the whole fork is carbon, if the steerer is aluminium or steel then just use a regular star nut if you want and it's not a big deal if they steerer doesn't poke out the top.