A while back I was reading the SMB IT Journal. For those of you who haven't heard of it, the Journal is written by an IT Manager named Scott Alan Miller and focuses on information technology from the perspective of small businesses. For a variety of reasons, that market segment has different needs than large corporations. In that vein there was one post about the differences between IT generalists and those who focus on a particular specialization such as networking or application development. Miller's main point was that they each inhabit separate markets and the more one goes down a chosen path, the harder it is to switch tracks. For those of you interested in information technology, the article was a fascinating read and well worth checking out at the above link.
There is a similar dichotomy within information science. Academic, public, and special libraries all have their own unique needs. Moreover large libraries and small ones also are very different regardless of what type of institution they are. So someone who works in a research library will likely be doing a job which focuses on one particular aspect of librarianship such as reference, cataloging, or systems. The same is not as true of archives since so many people work alone. However even here different institutions have different needs. So an individual who has spent their career working at a university archives might have trouble adapting to a small historical society where the main emphasis is on outreach.
Moreover the different branches of the information science tree are quite dissimilar from each other. Libraries, archivists, and data scientists typically come from the same programs. Of course there are specializations, but upon emerging from school with an MLIS it is entirely possible to start a job in a different part of the profession than one expected. An example would be training to be an archivist and then taking a job as a librarian. But once such a choice has been made, forever will it dominate your destiny. That's perhaps a bit melodramatic, but my own experience has been that after about 18 months working in an academic library the archival world seems very distant.
But information science is not IT. We don't have the depth of knowledge that they do. That's not a criticism even though it may sound like one. Consider the breadth of certifications available just from the Computer Technology Industry Association . Or those offered by vendors such as Cisco, Microsoft, and VMware to name a few. When viewed in that light it's easy to see why some IT people get locked into a particular path. The amount of learning one must do to make the boxes truly sing requires as much. One must also consider how fluid our field is. Archivists regularly work within libraries (whether or not that's a good thing is a different matter) and some jobs straddle both worlds. And records managers work with the same materials archivists do. There are also lots (and lots) of jobs which don't fit neatly into any box. Just check out I Need A Library Job.
As I wrote back in September many of these divisions are artificial. In that sense we are not at all like IT. We aren't separated by the sort of vast technological gaps those folks are. Yet the barriers created by standards can be almost as vast. Sure a librarian can be trained to do archival description or a records manager trained to do appraisal. But there is a learning curve in doing so. That is why collaboration is so important. Nobody knows everything. And the key to that collaboration is understanding that these silos we've constructed around us are really of our own making.