When you own a brick and mortar shop and you have reached your peak but still are eager to grow, you simply get a bigger place or open a second or even a third store location.
The same goes for your e-commerce store. Same, but different.
You see, opening several online sales locations, shops and marketplace seller accounts will create some truly unique challenges. How will you set individual pricing to stay competitive? What about synchronising your inventory? How will you handle all those different handling and shipping obligations?
It gets very complicated, very quickly.