It looks like some people are not reading the definition of "disruptive technology."
The term disruptive technology was coined by Clayton M. Christensen to describe a new, lower performance, but less expensive product. The disruptive technology starts by gaining a foothold in the low-end (and less demanding part) of the market, successively moving up-market through performance improvements, and finally displacing the incumbent's product.
By contrast, a sustaining technology provides improved performance and according to Christensen will almost always be incorporated into the incumbent's product.
The theory
In certain markets, the rate at which products improve exceeds the rate at which customers can learn and adopt the new performance. Therefore, at some point the performance of the product overshoots the needs of certain customer segments.
At this point, a disruptive technology may enter the market and provide a product which has lower performance than the incumbent, but exceeds the requirements of certain segments thereby gaining a foothold in the market. Christensen distinguishes between low-end disruption which targets customers that have been overshot and new-market disruption which targets customers that could previously not be served profitably by the incumbent.
The disruptive company will naturally aim to improve its margin (from low commodity level) and therefor innovate to capture the next level of customer requirements. The incumbent will not want to engage in a price war with a simpler product with lower production costs and will move up-market and focus on its more attractive customers.
After a number of iterations, the incumbent has been squeezed into successively smaller markets and when finally the disruptive technology meets the demands of its last segment the incumbent technology disappears.
Examples of disruptive technologies
Disruptive Technology/ Displaced Technology
Printing press/ Manuscripts, Scriptoria
railways / canals
the automobile / railways
digital cameras / photographic film
mass-market cellular telephony / fixed-line telephony
voice over IP / analog and fixed digital telephone systems
ADSL / ISDN
Internet Protocol suite / proprietary or fixed-configuration networks
EIDE/UDMA hard drives /SCSI hard drives
minicomputers / mainframe computers
personal computers / minicomputers
Personal video recorders / Video Home System
Desktop publishing / Phototypesetting and manual pasteup
Linux and BSD / Unix
Not all technologies promoted as disruptive technologies have actually prospered as well as their proponents had hoped. However, some of these technologies have only been around for a few years, and their ultimate fate has not yet been determined. Unresolved examples of technologies promoted as 'disruptive technologies'
Music downloads and file sharing vs. compact discs
ebooks vs. paper books
e-commerce vs. physical shops
open-source software vs. proprietary software (for example Linux versus Microsoft Windows, although Linux has already largely displaced proprietary Unix)
Failed technologies originally promoted as 'disruptive technologies'
Betamax
Laserdiscs
Cold fusion
Japanese fifth generation computer systems project
Virtual reality
3G
WebTV
8-track tapes
