This is survivorship bias. What you don't see are the spots that have disappeared because there wasn't enough demand to be profitable. The examples you've giv

This is survivorship bias. What you don't see are the spots that have disappeared because there wasn't enough demand to be profitable. The examples you've given are being used effectively because the price points have dropped to match demand for those specific service spots. Advertising follows user attention, and as attention shifts mediums so does the advertising. That doesn't mean there is an oversupply in the advertising industry, it just means that it has liquidity (more so than physical goods like lumber).