It's really not some conspiracy to keep black people looking as dark as possible, which is nothing to be ashamed of to begin with. Darker complexions are gorgeous, in my opinion at least. To my knowledge, it's because it's full of dangerous chemicals, which are obviously terrible for your skin. Yes, I know you're going to bring up tanning salons and there is no denying they're also bad, but not nearly as the stuff people use to bleach their skin, and tanning salons are also not just used by white people, so... it's not a one-race perk, so to speak
It's like a fair person wanting to be fairer. It's impossible. You can tan safely, because we have found ways around that (thankfully!), but lightening skin is harder to do, safely. Not to mention, the current methods make people look odd imo. They look more "grey" and almost ill, not really "lighter". It's like saying, "Why was I born with these coloured eyes". You gotta try and accept it sis