I'm deeply suspicious that an entire profession has changed the way they behave in just 5 years. Moreover, I think you're ignoring a few things. | One is that companies can only spend money on marketing they have cash to invest. In a sudden downturn, cash may become scarce. Another other is that in extreme circumstances, panic is a common reaction. Even if the marketing director is perfectly rational, getting an ad budget may not happen if the CEO and the CFO are waking up in the middle of the night trying hard to figure how to keep the company from bankruptcy.

And a third, and possibly the biggest, is that it may be perfectly rational to pull ads now. There are whole classes of things that people can't really consume right now. All travel. All entertainment. For many, anything they have to leave the house to get, including big-ticket items like cars. And consumer psychology in a recession drives people to minimize discretionary purchasing, stick with familiar brands, and be more skeptical of anything new or unfamiliar.

It's also important to realize that advertising is an arms race. A lot of advertising spending is only required because other people are also spending. E.g., everybody in the world already knows what Coca Cola is; they advertise not to inform, but to maintain dominance. So it's perfectly plausible that a lot of places will cut spending and see nothing change because their competitors cut spending too.