Is there any reason the verb "throw" should be used here? I thought the verb "hold" or "open" is easier to express meaning.
Answer from a Native speaker
"Throw a party" is an informal expression meaning to hold/have/host a party or social gathering. "Throw" is not meant in the literal sense here! It takes on a meaning similar to "hold," "host," or "put on" in this context. This expression is only used for informal parties and cannot be used to refer to formal events. Ex: I'm going to throw a surprise birthday party for my friend. Ex: We threw a party for my parents last weekend.