Sounds doubtful - normal daily contact with people probably spreads germs efficiently enough without kissing being required.
What I have read, and verily believe to be the case, is that animals rely on scent more than anything else in identifying each other. So those who are in the same family group mark each other with their scent so that they can truly be recognised as ‘one of the family’. This is one reason your cat will rub up against your leg, they are marking you as an honorary member of their clan!
Kissing (be it on the cheek or, more so, on the mouth) spreads sebum - skin oils. These contain OUR scent. So when WE kiss someone WE are marking them with our scent - and can more easily recognise them as friend/family rather than stranger or foe.