Exactly, and it doesn’t mean that Rotten Tomatoes is somehow involved in the review manipulation. It is obviously possible for an external party to influence the audience score, they just need enough money to buy tickets that can verify. It’s probably a much easier way than pressuring RT to manipulate the reviews if you have the money (and maybe even an interest in funneling that money into movie earnings)

That most people wouldn’t even think of buying a ticket and thus can’t post a review almost definitely plays a part as well.