You see, running a brick & mortar store can be complicated and costly. As you are selling products the traditional way, you have lots of things to deal with. You need reliable wholesale suppliers, you need to stock inventory, fulfil orders, prevent your warehouse from emptying, deal with customer service and complaints, and a lot of other things. All these activities take your time and require much capital.
Today, you should be glad because you can start your Own Online Store immediately without a single product of your own and without all the hassles compared to traditional stores.
Moreover, nowadays you do not even need to create or manufacture a single product of your own to start an online clothing store and be successful at it.