AMP really isn't a "cryptocurrency" per-se, it's an Ethereum token. You can't really "mine" it, the tokens are pre-generated as a smart contract and managed from the Ethereum network. Like most of the other Ethereum tokens, the exchange fees are insanely high at the moment.
Yes, it looks like they're trying their own off-network exchange system to get around the exchange fees. Guess what, though? There are at least a dozen other tokens trying to do the same thing.
I usually consider Ethereum tokens like AMP and SHIB (that new Dogecoin clone) to be "pump and dump" scams, mostly because they're easy to create without any real development effort. Hell... it's so easy to do that I made one myself. What do you think Coolcoin is... it's an Ethereum token!
Edit: Coolcoin is not a "pump and dump" scam, though. Or, if it was, I really sucked at pulling it off. If anything, Coolcoin works more like a "Stablecoin", as the exchange rate has been 1,000 Coolcoin to Space Kitty T-Shirt for years now