Believe it or not, people used to physically borrow movies from shops and return them 2 days later!!! That doesn't mean that I can still walk to my newsagents and borrow a copy of Pulp Fiction on VHS.

Things change, and Facebook and Google are now the big players in online advertising, accounting for a large majority of the ad market. Other platforms exist, of course, but by cutting out Google Ads and Facebook you're going to be targetting a very different user base and are cutting out a significant share of the market.

Online Facebook + Google take something like 50% of all ad revenue. Since the product being advertised is a website, offline advertising is probably a lot less effective than online.

It did, and it still does. The biggest difference is that now, FB and Google and a few others have a scope that is an order of magnitude larger than all other advertisers combined. They've gained almost total market control over advertising, hence the word monopoly.

and then there was a massive revolution in the way that people consumed content, and now FB and Google account for the vast majority of advertising consumption (not spending: consumption)