Why press release and press conference have been included as a method in advertising?

To be more accurate they are a form of Public Relations not Advertising.Public Relations deals with the proper dissemination of company-related information to its stakeholders to ensure that the company image is held in a certain light.Whereas a press release/conference may achieve  a  degree of visiblity for a company it is quite short-lived.Advertising usually needs drawn-out periods of time to achieve some good results.

The scope of advertising is essentially, any activity that creates awareness to the public and drives the message across. We even now have New Media Advertising which includes the use of social media and the internet as they have become touch points of consumers. Press releases delve into the story behind a product, service or event. Press conference is the field day of media people to get as much as first hand information from the source of the product, service or event. Once the articles are published, it informs people of the product, service or event. Therefore, it created awareness and drove the message across without the fancy images.