Selling shirts on sites like teespring and teepublic isn't plain and simple, you have to do a hard work. You even have to invest for ads just to sell few shirts. Steemit change it all on steemit you can upload your designs and advertise it for free at the same time you can earn money on how many upvotes it can get and imagine (example: 300 people) who sees the design buys your shirt you'll have money on your steemit and you have waiting money on your teepublic or teespring account.
Just imagine that your using ang SUPERMACHINE that can generate you money both ways. Steemit made it simple your shirt is dope you get followers, you get followers you get upvoters, you get upvoters you get the chance of selling shirts you get to sell shirts you'll have some extra money.
ITS LIKE WORKING SMART , NOT WORKING HARD :)