Its not hard to answer your question.
Because your way is outdated.
Yes the new method still rely on rng, but you can get much higher rank with the state you want on it.
The old method after they nerfed pure boon compound 3 twice, its just not worth to use it anymore.
The new method is more complicated, but totally worth.
Check the following article, you can learn the new way to forge.
At least, 90% of my gear are around rank 320 - 360 (aoe hammer with damage lvl 9 + lvl 6-8 action speed or durability) Weapon can be around 360 - 390 (depends on rng)
And your way can only get the gear below rank 300, only if you are super lucky, you have chance to hit rank 310 or slightly higher number.