Single Tickets

Can you not buy just one ticket to a game? Every time I try it says “selecting this seat will leave a single seat stranded, please try another seat.” But there are no single seats available in that section. Do they just want me to spend more on a better section? I don’t get it. I just want the replica ring honestly, and to enjoy my day off but I guess I won’t be doing that at Minute Maid haha.