But why is there only one display port...
Because they assume you're gonna attach it to you most awesome gaming PC.. The ONE pc to rule them ALL..
OK, but let me just do some sweeping generalisations:
This is the best monitor according to tp
A lot of people who have experienced multiple monitors would say that three is the optimal amount of monitors to use (no bezel in the middle of your field of vision, don't have to move your head much, etc)
Most people with "good" gaming PCs have between one and two GPUs.
Most "good" GPUs under $400 have only one display port output.
Therefore, in order to run the optimal number of three of these fantastic screens, you need to have three GPUs, ($900-1200) as well as a PSU that can power all of them, (~$150) a mobo with the right PCIE slots to run them (~$200) as well as the price of the screens themselves ($2100) meaning you are paying over $3000.
Any other normal monitor, you could run three of them off one card. That's all I'm saying.