Not at all, there is a lot of option for mining, some unknows altcoins can be even more profitable to mining over Eth or some big coins, you need to make some good research to find a good one.
You forget to mention the unknown coin has the more chance to make us get a big zonk for the time that we have wasted to mine such garbage coin. I have seen some old thread that said the creator has tried to main unknown coin but it became a coin with no value.