So much anger.
You'd be pissed off too if some troll wasted your $300 per hour (opportunity cost) time for several hours. He could have raised his points with much less verbiage, rancor, and direct to the point on specifics. We could have concluded his education with a few cordial posts. But no, he was determined to be an asshat and was trying to humiliate me. It backfired on him, because I am somewhat expert.
There is a perception that a long POW chain has a lot computation work behind it. This is not always true. POW difficulty changes to meet the target block generation period. There is no guarantee that a longer block chain has more work than a shorter chain.
Incorrect. A correctly programmed PoW block chain will compute the cumulative difficulty of the chain. This can be computed/verified mathematically from the number of leading 0s in each PoW hash for each block.
So I accept checkpoints. They are cheap and make it highly difficult for attackers to workaround it.
They are not cheap. They waste the entire block chain on a power vacuum clusterfuck. Please read the OP and all the links and think more carefully about the critical importance of the Nash equilibrium. Study what happened to Ethereum.
This issue becomes critical as your block chain scales to a $billion valuation and is a serious contender in CC.