This is an interesting comparison.
WordPress is essentially a blogging platform and its great at what it does. With time the flexibility of WordPress has evolved, thanks to the plugins, themes, and the developer ecosystem.
However, WordPress is not the right platform is you are looking to build an online community. Sure, there are plugins to add membership functionality and social components, but there is not much flexibility in terms of how you want to organize and structure your community.
A community platform like Tribe has been designed from the ground up based on the preferences of modern social media users, the way content consumers are looking to interact with others and get personalized recommendations.
Tribe's modularity allows you to easily enable or disable different social elements like Q&A, discussions, group system, reputation, and more.
In the case of WordPress, the flexibility of integrating plugins and themes with the open-source solution can also be a negative issue - there is always a constant tussle and blame game between theme developers, plugin developers, core WordPress developers whenever something breaks. And invariably the site breaks if it needs synchronization between multiple extensions.
However, if you going to use WordPress as a simple CMS to write content and get comments, it is actually amazing!
Another issue with WordPress is its popularity. Yes, that makes it vulnerable to security threats -- everyone from script kiddies to seasoned hackers try their hands on WordPress. In the case of Tribe, the onus of keeping everything secure, managing the hosting, database, and taking care of all the technical mumbo jumbo lies on our team.
Also, the technology stack of WordPress is old and that makes it difficult to adhere to modern changes. Tribe Platform is built on the hottest tech stack and that allows us to deliver better user experience (the upcoming revamp will make that highly evident).
For those who are already using SaaS apps (e.g., HubSpot, Shopify, Intercom, Slack, etc.), Tribe offers direct integration and allows additional integration with Zapier as well.
Regarding traditional forums - I believe this linked resource56 can help.