I agree with you. We are not talking about altcoins that can outperform Bitcoin but there are not even any altcoins that are similar to Bitcoin. The OP asked about altcoins that are similar to Bitcoin in terms of mechanisms such as halving and supply size. There are actually several developers who are trying to create coins similar to Bitcoin. They minted only 21 million coins the POW way. I've forgotten the coins but as far as I know they weren't successful because they were just imitating Bitcoin.