Everytime I hear the word 'dogecoin' I break out in a rash. Anyway, I think the answer is because it is still able to be mined on little more than a home PC and this is constantly increasing its user base. There is a massive dogecoin community out there all supporting this worthless ancient joke coin.
However, it does one thing well, and thats introduce people into the wor!d of crypto, its a kind of startercoin and again due to its massive online community and its tipping ability on reddit for example it remains extremely popular. That popularity and userbase that Steem needs to flourish.
If proof were needed that popularity and community were the most important attributes in crypto, in its own way, dogecoin proves it and in this respect, perhaps Steem could learn a lesson or two.
This is why Dogecoin is holding its own. Its still growing its userbase due to its accessability.
Who knows? Not every cryptocurrency is going down. Some of them are even going up, Why they are going up?
Just see the https://coinmarketcap.com/gainers-losers/ for more information. That webpage contains the biggest gainers and losers in the last 24 hours, but you can also check the last 1 hour or the last 7 days on that webpage by clicking on the appropriate/proper link(s).
I am guessing because it is not perceived by users/investors as a relevant crypto so it is hardly affected by major changes in the crypto-market.