dogecoin was very useful has a introduction to cryptocurrencies.
few got to see the value of bitcoin has digital cash till they used it and saw how nice it was to send money almost immediately from one person to another.
at a time when getting the bitcoin needed just to cover the bitcoin transaction fee from a faucet took weeks, with doge it took seconds.

it was also a great coin to mine if you wanted to try mining, unlike bitcoin or litecoin, with dogecoin in a week you had lots of doge to play around with.