The problem with selling to the consumer on the Internet is that it favors price comparison and, as a result, discounting. The moment one brand starts offering a product for a slightly lower price than the competition, it triggers a discounting spiral that makes everyone worse off—it’s a vicious self-reinforcing feedback loop.
It’s very hard to escape this, which is why luxury brands have refrained from selling online for so long and control their distribution so tightly: they don’t want to start a discounting war that will end up diluting the brand in the eyes of the consumer.
Unfortunately, aggressive discounting is still the main strategy of most multi-brand retailers/fashion marketplaces.