I guess they are going under the radar of bing as advertising in such way is not allowed as far as I know (in the US). Hence why Google doesn't allow it either.
I'd also recommend going for Wordpress since you'll have much more control over what you do. Else go for at least the paid version of Wix, or you may regret it later. Will be following this thread in case you decide to go for Wix, curious!