Horribly designed sites can dominate old markets too. Amazon is the perfect example of why design doesn't matter. Likewise Craigslist and eBay... the list goes on and on. It's all about marketing and luck.
The more you need a product the less it's design matters. The less you need a product the more it's design matters.
This is why de-facto standard utilities like Amazon, Craigslist, eBay do not need to be "beautiful"
If what your business provides is a basic need of somebody, a terrible UI/UX wouldn't stop the guy to use your website and get his job done. For example, look at many of the University websites.