Dear teachers, what does this sentence mean?

[atoom]

A said: Anyone else noticed that there have suddenly been lots of landmark posts?
B said:Yeah, I guess its because alot of people joined up around that time..
C said:What does that have to be with landmarks? The only members that joined this year and did a landmark are Paradox and EWild... all the others landmarkers are from 2001..

the question is:

what does the bold part of sentence mean?
in my dictionary, the phrase "have to be" means "be something without doubt" or "definately be", plus it is oral language, so this sentence is "what is that with?" OMG, so strange... i'm confused, i think there is something wrong with my comprehension, could you help me?thanks!

[trustM]

I guess it's probably "what does it have to DO" not "BE"

[atoom]

i'm sure it's "be" there

[Casiopea]

A said: Anyone else noticed that there have suddenly been lots of landmark posts?
B said:Yeah, I guess its because alot of people joined up around that time..
C said:What does that have to be with landmarks? The only members that joined this year and did a landmark are Paradox and EWild... all the others landmarkers are from 2001..

"What does that [what you just said] have to do with" means, how is that ('a lot of people joined up around that time') actually related to my question about 'landmark posts'? How is it related? What's the connection?