The Internet did not have the advertising presence it does now when it was conceived.

Do you mean back when it was only the government and universities connected to it, before the web existed? Those times were very different. Practically user was contributing to the internet some way, either through time (like actually creating the software to use it, and once the web existed, creating sites) or money.

These days, there’s a significantly larger number of freeloaders that want everything for free, without contributing anything back. So far, advertising has been the only effective model to support such users that don’t want to pay.