Drinking tea is a very emotional and slow thing, and it is the most appropriate way to talk about business. Without this formal occasion, everyone's opposing interests are not so hostile and obvious. Just like communicating with friends, it is very pleasant to do business well. And when talking about business, you must hold your breath, which is more important than patience, so drinking tea is also a time-consuming leisure, which can calm people's mind.
Another reason is that drinking tea is a very fashionable thing, which can reflect a person's ability to treat people and people, so bosses often choose to drink tea in order to make themselves look taller.