I think you're overthinking this, CH. Say someone has ONLY tried Franks, Tabasco, El Yucateco, and Sriracha. They say "Out of the four hot sauces I've tried, I like Sriracha the best because it's a great blend of heat, flavor, and consistency." See? They've chosen a favorite. As this person explores more sauces, their favorite will likely change, as it happens with all of us that have tried numerous sauces.
You bring up that it would be silly for THP to hire a blogger who has only tried a few sauces. Yes, it would, but I don't understand how that relates to having a favorite? You sound like you wouldn't trust the judgement of someone that has only had a few sauces in a discussion of favorites. Did you consider that a person like that will most likely name a favorite that you've already tried? A person like that will have most likely just tried the hot sauce staples.
I'd hate for a newbie to come across this thread and think that his/her opinions won't be valued until they try a ton of sauces.