2
I agree with your observation. The wiki's assessment of the weakness of ECB being a lack of diffusion is not very precise. I have a feeling that they're using diffusion in a generic sense, not the exact definition of diffusion in cryptography. Diffusion in the exact cryptographic sense happens inside the block cipher like AES.
What we need on the higher ...
1
First of all a monoalphabetic substitution cipher can be the concept of monoalphabetic substitution or an encryption only using this technique. That means, Ceaser is a monoalphabetic substitution, because it uses this concept. The difference to the "real" monoalphabetic substitution is, that the key generation is not completely random.
I personally ...
Only top voted, non community-wiki answers of a minimum length are eligible