Yes, because they are a digital currency. You can stop calling them altcoins if you wish though and just call them cryptocurrencies instead. Maybe altcoin will go out of fashion eventually but you can't really force people to change but you can lead by example.
The term alt coin has been used for so long it's like a household name now. Trying to get people to call them a new name is like trying to stop people calling vacuum cleaners hoovers.
Plus, it makes sense as long as all of them are living under the shadow of the Big