TV remnant inventory is usually sold at the local level and is nowhere near as large a percentage of of the pie as it is online. It's also hard to "create" more

TV remnant inventory is usually sold at the local level and is nowhere near as large a percentage of of the pie as it is online. It's also hard to "create" more inventory on TV - not so online; which is exactly what publishers do when their CPMs start to drop. They'll add more slots for banner ads, interstitials, split articles into multiple pages... This increases total revenue for a while, but ultimately crushes your CPMs. There's a floor on TV advertising of about 16-20 minutes of advertising per hour. More than that and you start to turn your users off in huge numbers.