The only barrier to entry you should care about
versiononeventures.com
versiononeventures.com
Demand-side scaling is one approach to lock-in. Others include APIs, open/closed data policies, utility, interaction with other services, ease-of-use, and more.
Hal Varian and Carl Shapiro's Information Rules is a far more complete look at various elements of lock in from both a provider and consumer perspective. http://www.powells.com/biblio?isbn=978-0875848631
This is a great post. There was lots of thought previously that network effects could be built using vendor lock in (switching costs), first mover advantage (technological advantage), and preemption of scarce assets. Demand-side benefits of scale really are a preemption of scare assets, whether it is consumer attention or positioning in the app store. @bwertz has provided a great summary of why the rush for traction and the prevention of others that matter. #mustread
Now to be honest, the Mailchimp example in the article sounds fairly innocuous compared to Facebook. They're just able to give you extra data and better stats (from what it sounds like; only skimmed) compared to an upstart service. It's a less extreme example because the value-add from network effects is a smaller proportion of the overall product.
But the principle is the same, and this is yet another reminder that Silicon Valley capitalism is as amoral as any other kind. I look forward to someone disrupting the paradigm of non-interoperable web services that let businesses lock people in like this. I don't know if that kind of disruption will have a business plan behind it; I suspect it may not be VC-funded.
If the market creates an innovation engine, then participants in the market will compete over scraps. Unix, the Windows application environment, Apple and Android marketplaces, consumer fashion.
If a company creates an innovation engine, then it can ride a stream of development that gives it a persistent advantage: 3M, Edison, Apple, Google, Intel. Possibly IBM (though I'd count its success on other factors, despite a few periods of significant innovation).
Contrast this with companies which created one big idea and camped on it for a long time: AT&T, Xerox, Boeing, Microsoft, Comcast. These have essentially leveraged economies of scale, regulatory environments, and monopolies to capture and retain a market for an extended period of time during which little if any real innovation happened. Oftentimes these companies actively discouraged significant new innovation (AT&T and IP telephony, Boeing and high-speed rail, Microsoft and OS alternatives from DR-DOS to OS2 to Novell to Linux, Comcast with municipal broadband).
It depends on whether or not your goal is market dominance or advancing overall conditions. I'd like to see an innovation-based strategy encouraged, and demand-side benefits of scale doesn't deliver on this.
Microsoft is a business built entirely on network effects -- both their operating system business (everyone developed for Windows because it had all the users; it had all of the users because it had the most applications) and their office suite business (Office was taught in community colleges because it made you desirable to the maximum number of employers; businesses standardized on it because it was easy to hire workers that already knew it, and because they could exchange files with other businesses.)
Microsoft enriched itself enormously through network effects -- and I would argue, enriched society as well, compared to an alternate timeline where operating systems and application software were fragmented and software and skills were not portable. Though I do wish they'd done a better job with the win32 API.