Small and medium-sized businesses (SMBs) face many of the same challenges and complexities as larger organizations, but they don't have the same resources to pursue solutions to their challenges. Identity management is a case in point as it can be very expensive, and the more custom the solution the higher the cost to deploy and maintain it.
SMBs are forced to get the biggest bang for the buck with strategic purchases primarily because revenue generation is not as predictable as it may be for larger, "more stable" companies in the Fortune 500. Given that there are many more SMBs than Fortune 500s, it is essential that SMBs are able to use an off-the-shelf approach to identity management, as building custom solutions is like trying to repeatedly reinvent the wheel for each SMB.
Building blocks
This is not to say that SMBs all need the same solution, but that the fundamentals of deploying such services do not change across industries, and SMBs can configure building blocks that already exist to handle the solution rather than creating custom solutions.
Traditional identity management has long been thought of as non-predictable in terms of scope of effort for deployment and maintenance, which doesn't scale well for limited budget, fixed-price constraints attributed to the SMB market space. Unlike some larger organizations, SMBs do not have the luxury of doing "whatever it takes" to provide the solution needed. SMBs need best practices with predictability, finite projects timelines with clear goals, and a finish line that doesn't move.
Typical identity management deployments cannot provide this level of predictability, specifically deployment models that start with a blank canvas and provide little direction other than which programming language you should use. These types of deployment models don't scale for the SMB space. The message for these types of models is, "you can do whatever you want when you write your own code." Sure, this is true, but only if you have a rather large budget for deployment consultants and even larger staff budget to support and upgrade the solution.