Just like humans, wild animals take time to groom and socialize and in the process provide relative protection for each other against predators.
Zebra have great eye sight but the giraffe has advantage of height to spot danger from far. This offers other grazers and browsers adequate time to make evasive maneuvers to get out of harms way.
So you will notice that also antelopes prefer to hang out with zebra and giraffe as a safety precaution even as they graze and socialize.
And these animals have a role to play in nature's health and ecosystem sustainability. They are not simply a tourist attraction but active players in the promotion of biodiversity