Applications like those provided by Google, Twitter and Facebook only achieve their popularity based on their widespread use, thus the need to keep them free and supported by advertising. Just like television, radio, the heavily-subsidized news industry and many, many more programs that rely on sponsorships in lieu of publicly-funded grants. These programs create jobs and in many cases promote education and health awareness through outreach, not to mention life-saving services and charities who without the use of advertising would not be able to sustain themselves. Advertising is a fact of life and has been socially pervasive since times immemorial. Advertising is communication and vice versa. Without it we would not be able to function as a society.
* that tv license they have in the UK is whack.