The Difficulty of Making Something Viral

We all talk about the need to use viral marketing. But, increasingly, I'm becoming convinced that it's nearly impossible to actually plan. Phyllis Korkki, in the NYT, seems to support this perspective, in this very short article:

According to a report by JupiterResearch, “24 percent of marketers have run a
viral marketing campaign, but many struggle to get the expected buzz.”

Ditto this Techdirt article - re virally-launched apps & products - from April of this year:

I've seen tons of "viral" apps out there that went nowhere. And it wasn't
because they lacked that "engineering alchemy" or a "viral expansion loop." It
was because building a business is difficult and takes a lot of effort, and not
everyone succeeds at it. Penenberg's article is the worst kind of business fluff
article: not only is it wrong, but it will get people to think that it's easy to
do something that's actually very, very difficult.

I'm not saying that we shouldn't put ourselves in position for a viral effect. We should. But building something, a marketing effort or product, for which a viral effect is required for success ought not to be invested in too quickly.