A Simple Solution to prevent 51%, DoS, and Double Spend attacks

[boliu]

Would a simple implementation of preventing any miner or pool to submit consecutive blocks solve these attacks?
                     

[TheRealSteve]

How would you determine that two submissions come from the same entity?  Assume they can: change the coinbase text (as they do), change the payout address (as they sometimes do), change their IP address (insofar that even matters), etc.

Additionally, your suggestion would not help against collusion (i.e. two miners working together).