that noob don't know what he's talking about
The n00b is you. Read on...
I just stumbled across this critique and wanted to add a response:
1. Users attempted to flood the steem network with transactions, validating nodes included transactions at the specified limit.
2. There is a limited supply of computational power
Well yeah if you have bounded set of validation computational resources with the bound enforced by whales, then you have a centralized monopoly lacking free market competition. Replicating VISA isn't interesting. I was referring to a decentralized blockchain, which your DPoS is not.
Your remaining points about POW on each script and Nash Equilb are completely missing the point by getting lost in the weeds.
An attacker can submit a transaction for validation that fails after the allowed time (say 2ms). The attacker generates the transaction but doesn't run it themselves, which gives them an advantage over the defender.
If the defender sets an arbitrary POW requirement on a per-connection basis, then they can force the attacker to perform a 2ms POW that is validated in 1 us before attempting to process the script. The attacker would have to redo their POW for each peer they want to broadcast to.
You entirely missed the point which is that the asymmetry is relative to the other honest users which have to do this PoW and don't have access to a mining farm (or at least a very efficient ASIC) whilst the attacker may. Of course verifying a PoW solution is always asymmetrical to finding a PoW solution. So that could not have been my point.
Anyway, preventing SPAM is a trivial problem compared to attempting to scale ETH.
Neither are trivial problems if you want a truly decentralized blockchain. In fact, no one has yet solved these issues for a blockchain that doesn't become centralized due to economies-of-scale.