Instead of asymetric encryption, why not use two One-time pad?

Question

Why is the following protocol never used to share a symetric key between two parties ? ⊕ is the XOR operation.

Alice has M and wants to send it to Bob. Alice generates K₁ randomly. Bob generates K₂ randomly.

• Alice has M.
• Alice : M -- ·⊕K₁ --> M⊕K₁
• Alice sends M⊕K₁ to Bob.
• Bob : M⊕K₁ -- ·⊕K₂ --> M⊕K₁⊕K₂
• Bob sends M⊕K₁⊕K₂ to Alice.
• Alice : M⊕K₁⊕K₂ -- ·⊕K₁ --> M⊕K₂
• Alice sends M⊕K₂ to Bob.
• Bob: M⊕K₂ -- ·⊕K₂ --> M
• Bob has M.

Of course, K₁ and K₂ need to be the same size as M.

Answer 1

Here's why it doesn't work:

Suppose someone in the middle hears $M \oplus K_1$, $M \oplus K_1 \oplus K_2$ and $M \oplus K_2$.

Then, what they could do is xor the three of them together, giving:

$$(M \oplus K_1) \oplus (M \oplus K_1 \oplus K_2) \oplus (M \oplus K_2) = M$$

Thus recovering the message.