A large part of housecat vocalisation toward humans isn’t goal-directed communication, but rather, affiliative signaling: a simple call-and-response protocol which establishes that the participants are part of the same social unit. Amongst themselves, most housecat affiliative signaling is non-vocal, but humans aren’t really physiologically equipped to respond to such signalling in a feline fashion, and cats, well, they’re adaptable.

Which is to say that when your cat yells, and you yell back, so the cat yells again, and so forth, what you’re really saying to each other is “hiiiiii~”.

This is why it is important to meow at loved ones.

A largish percentage of human vocalizations are this, too!  When your human co-worker says “Workin’ hard or hardly workin’?” or comments on atmospheric conditions or other readily-observable features of your surroundings, or generally statements that seemingly convey no useful or novel information whatsoever, the true purpose of these vocalizations is to develop and/or maintain the social unit of the workplace!   In effect, they are saying, “We are experiencing this situation together.  We often experience situations together.  Let’s be allies!”

Some humans will even make vocalizations of this kind to complete strangers, such as when waiting in a line or using public transportation.  This behavior is especially common in situation that may involve some form of inconvenience or frustration, such as waiting in a long line or experiencing a delay.  In these contexts, the vocalizations communicate, “We are both experiencing the same unpleasant situation; let’s not make it worse by being aggressive to one another.”