LOL.. going by your definition, most of the coins in top 10 right now are "old coins". Bitcoin was invented in 2008 and was first mined in 2009. Ethereum ICO happened in 2014. Ripple's initial release was on 2012. In case of Cardano, the ICO started in 2015. Dogecoin was first introduced in 2013. So going by your definition, almost all of the top coins are "oldies". Among the top 10, I could find only Uniswap, that was created at a later date (created in 2018 by Hayden Adams and listed two years later in 2020).
If you are talking about coins that became obsolete after 2017, then there is a point. One example is TRX. Used to have a market cap of $15 billion. The current market cap is less than 1/4th of that.
Is it not a crazy thing that a project only a few years old can be considered old in this space? And Defi coins are even worse, if it is 2019 it is considered old and that is not even two years old!
Just goes to show the hype industry of defi and how short their lifespans are. If you think TRX is obsolete now,,, How about Waves:) I feel sad every time I think about it!