Word of mouth isn't viral
blog.aweissman.com
blog.aweissman.com
Viral is Hotmail (and the other examples the OP lists) - when a person uses the actual product, they cannot help but spread the message ("Sent via Hotmail. Register now for your free account"). Great observation that I had previously missed.
No real value judgment for or against word of mouth or viral, just that they are very very different, and require different ways of thinking about apps services.
The company I work at has been seeing 20% growth per month for many months now, and we don't seem to be meeting his definitions: "A user's usage of those products - without anything more - markets the products themselves." We do facilitate the word of mouth process by including a feature that allows users to share with Facebook or Twitter, but there's nothing inherent in our service's usage that makes users market the service for us.
Don't assume that. Viral is a class of mechanisms and is orthogonal to growth rate, not a descriptive term for growth that means "good".
Also, Weissman is speaking of whether a service is in-and-of-itself 'viral'.
There's the related but somewhat different idea of "viral marketing", where some aspect of a marketing campaign is designed to get people to pass along the marketing message. A shocker or stealth marketing campaign that's so interesting people pass along its details is 'viral', even if it's for a non-viral product like a blockbuster movie.
Your tool to help users tout your service is a mild form of 'viral marketing', but it doesn't make your service 'viral'.
Are viral services spread "like a virus" because their use is automatic promotion, like how having a virus automatically exposes people around you to it? If users consistently choose to promote you because they are compelled by how awesome the service is, doesn't that amount to the same thing?
Not in the sense Weissman is talking about. Yes, if you squint, any positive word-of-mouth is passed along vaguely like a virus. But then everything is 'viral', and the word has lost its value for distinguishing products that are strongly and inherently 'viral'. Those that are 'viral products' are passed to more customers by their design and mechanisms of operation, which is different (and deserving of a unique label) compared to just 'good enough to remark to friends'.
Viral marketing is where company creates a campaign that is of interest of its own accord in hopes that it will garner attention and that attention will pass on the the product or service that being advertized.
A viral prodict is what this guy describes.
I think that a conflation of these two ideas might lead to the confusion that this guy is talking about.
I spread viruses because the virus makes me cough or sneeze. I spread jokes and urban myths because they make me repeat them to others. Online these are generally called memes or viral.
It gets confusing because he's not talking about funny videos, he's talking about a business plan. If your business was putting funny images of cats in front of as many people as possible for free then job done. If it's getting people to use a service or visit a site then you need to make sure that usage of your service is the thing that's passed on virally, not the content.
I guess part of it comes from the unfortunate use of "viral" conflicting with "word of mouth" which kinda sounds like a way to transit real viruses.
I can see why it's confusing for people, but I agree with you 100%.