Hey Ryan DeJonghe! This is a good question. There are a few reasons:

1. Wix allows users to quickly make a custom site. WordPress may take some getting used to, but range of what you can do is far greater on WordPress (not comparing the forums per se but comparing the two as a CMS from which I chose to run my website). While Wix offers an easy to use website builder, you can accomplish a lot more with WordPress over the long run. This is partially due to the difference in apps/plugins. Wix comes with nearly 200+ apps that you can add to your site. These apps offer a wide range of features like adding contact forms, gallery, comments, social media buttons, email marketing and so on. At the time of writing this article, there are more than 55,000+ free plugins available in the WordPress.org plugin directory alone. Not to mention, premium plugins available on other marketplaces.
2. Data portability. I’ve written about the importance of data portability before as it pertains to owning your own email list, but the same is true for site infrastructure. Data portability allows you the freedom to move your content away when you need it. Wix comes with very limited options to move your content to another platform. You can only export your blog posts in XML format. You’ll have to manually download your pages, images, videos, and other content. According to Wix documentation, all your content is hosted exclusively on Wix’s servers and cannot be exported elsewhere. WordPress makes it extremely easy to export your content. It comes with a one-click exporter that allows you to download your content in XML format. Since it is a self-hosted platform, you can also create complete WordPress backups, download your media files, and even manually export your WordPress database.

So I guess my main issue with Wix forums is not so much the forum functionality itself (it actually looks pretty nice), but the fact that I would need to use Wix over WordPress, which is a tradeoff I would never make. For the reasons above, but also because of WP’s robust community of designers offering sleek themes (I use Divi from Elegant Themes).

It’s worth noting that PeerBoard can be integrated with pretty much any CMS, whereas the Wix forum is an app limited to Wix websites.