I would certainly encourage my affiliate if they wanted to open their own website.
But with all the tools that SFI offers, I don't see the need, and your own website is a lot of work and expense.
But if they have the time, money and know how, by all means. And if they wanted their own website, to me, this is saying, they know what they're doing and this could bring in massive downline and sales.
So, basically, why would you tell an affiliate not to?