Although there are many different types of altccoin in the market. But l am not agree with you at this point all altccoins are useless. But some of them lost their value in the market due face different types of problems & not successful to maintain projects. That result they could not attracted the investors. But no doubt we rgain knowledge of market through altccoin. I think so.
in theory, if we see altcoins that have the same function, they are not much different from other road maps in general. But strong altcoins have a clear path to strengthening profits directed at fluctuations in their coins on the market. If this is not achieved, then they can be sure they fail and their coins are useless. But you are right about the knowledge and experience gained, especially between traders, investors, and developers.