I would say that the question is not whether you know the name of the person handling the cover letters, but rather if you are sending your application to a specific person (if the contact information provided in the offer is that of a specific person, and not firstname.lastname@example.org). In that case, yes, address the letter to them. (As you would address the e-mail containing your application to them directly, right?)
In all other circumstances, it doesn't matter. What you should research and mention in your letter, is the company (and the team/service, if it's a big company), why you would like to work there and be a great addition to the team. Mention the company/team by name and name specific examples that prove you took the time to address your letter to them, and that it's not a template sent to a hundred other HR services. The name of the person has no importance whatsoever, and as you said, the letter is bound to be read by several recruiters and team member. They know the application is going around, and they will not care if the name on the top is theirs or someone else's or a generic greeting. What they will care about is the content. As for the name, do whatever you are comfortable with!