Some customers prefer asking in a community because that can lead to responses from other customers (at times it can even be faster response than a company rep getting to respond). A good example is dev infra related companies, where a customer can get a lot of value by hearing from how other customers think about a specific problem. You don't get that through a typical customer support software which is one to one.

It comes down to preference. The trend is that companies have to meet where customers are already hanging. Some customers will prefer only email (and for them you still need a ticketing software), some will prefer social (depending on industry), and some will prefer chat/forum communities. If you want to stand out as a company (esp when you are starting out), you have to serve them where ever they prefer. Sure, if you have an amazing product with a strong moat, you have more leverage on how you want customers to interact with you. But that comes much later in a company lifecycle.