Why do people announce that they are going to sit by someone in church gatherings?

Question

There is a lot of psychology/sociology involved in this. I hope no one is confused but I have seen this behavior happen and an individual would be sitting by him or herself and someone else in the church would announce that he or she is going to sit by that person just before he or she sits there. Example Bob is sitting by himself and just before the meeting starts Tom says that he is going to sit by Bob, and he does just after he said that. Why do people do this? This is not a norm. Usually when people sit together no one announces it. This happens in like bible studies and other church activities, but not usually in actual sunday service

Answer 1

strictly for attention, as if they are doing something good.

Answer 2

well if i am at a family get together and I am sitting with aunt sally and I want to go visit with uncle bob, I tell aunt sally, "I am going to go say hito uncle bob." It's called not being rude. It is quite awkward if you sit next to a person and just get up and leave without saying why.