Can we please nerf devourer already

The item is balanced and needs no nerfs. Most of the strong champions with it use Rageblade and even so, they are still not considered strong at the highest tiers (competitive play like LCS).

Abuse their weak stages. Devourer champions are built to farm and scale. If you don't meaningfully exploit this stage (which for competitive is considered too big of a weakness), you will get outscaled hard. The other weakness they often have is a lack of CC.

If such champions like Yi are really a problem, they should be nerfed, not the core Devourer item which affects many champions (including Kayle, Kog JG, some Kindred builds etc.).

Learn to counterplay.