Agree that there can/should be a barrier, but Rep is not the correct one. It's too easily "gamed" .. that's all I'm saying, which I guess I didn't explain well enough. Read the whitepaper and you'll know what I mean. It's pretty simple math for why Rep isn't a true barrier when you factor in someone with enough SP to auto-elect witnesses.
RE: The History of Delegated Proof-of-Stake (DPOS)