Is interest sharing a cartel?

A recent post from Nicholas Carr's Blog A sharing of interests reminded me my desktop several years back. I used Arabesque Ecco Pro as a PIM, Winfax and Zmail for communication, Quattro and WordPerfect for work (I also used NotaBene for academic work, but that is beside the point). All those application interacted using Windows DDE mechanism. All of those worked fine in Windows 3.11 and to some extent in Windows 95. This was not a cartel or an oligopoly.
Does anyone recall those applications? They were lost in the feature wars of the 90's and DDE was replaced by OLE. Best of breed was lost to amalgamation and a so-called unified front end.
I see a need for specific applications and services which are unique and different, but interact with each other.
The danger exist that these "Shared interests" will try to lock the user to a predefined set of options, but it is still a better option then uniting all services into one vendor or provider.