Much has been written about the commonality or even the lack of it between Agile and CMM [1,2,3,4]. CMM claims to be a flexible model that can be tailored and adapted to many life cycles [4,5,6]. This facilitated attempts to bring-in the iterative life cycles and practices of Agile under CMM model [1,2,3,4]. However, the debate on their compatibility continued as is evident in Kevin Trethewey‘s blog, which is one of many of its kinds.
The continued discussion is evident enough that it is not sufficient to compare practice to practice and arrive at any reasonable conclusion about their overall compatibility.
The one difference that seems to have earned consensus amongst most of the published literature on the subject is "the people aspect" of these models [3,4,8]. While CMM has little people focus, Agile's foundation is people focus. In the context of Generation Y becoming a major part of the work force, this people aspect may become one of the main drivers for organizations to endorse Agile and reject CMM with or without Agile practices in it [9,10].
2. People Focus in CMM
There are multiple aspects of CMM and its implementation makes the people aspect take a back seat. As James Bach puts it "The CMM reveres process, but ignores people." 
Following is a compilation of some of these aspects culled from the available literature..
2.1 Historical baggage
Historically, CMMi's predecessor CMM was originally published in 1989. This date is much before the advent of Internet. Following is an excerpt from a relatively recent paper from SEI suggesting to embrace both Agile and CMM
"If we look at the genesis of the CMM, it predates the internet and nearly everything associated with internet technology. For that matter, CMM predates many software development, deployment, and infrastructure technologies, languages and methods. We've all learned a lot in the past 20 years. When the DoD set out to address their "software dilemma," the software world was different than it is today." 
CMM was mainly focused on models for high-risk, government contractor projects. In the age where there was not so much communication let alone collaboration channels established, the model had to be something that enforced accountability rather than expected it.
CMM later expanded to multiple other models and the latest being CMMi 1.2. However, the remnants of old times are present even in today's models. The following reference states that explicitly.
"While the language of CMMI, admittedly, may retain some of the flavor and phrasing of this context, each release of a CMMI model grows further away from these roots to embrace a richer and more dynamic set of contexts." 
The same paper goes on to explain how the situation worsens further by practitioners who don't move with newer versions of CMM that are made to suit to modern contexts. All this makes CMM and its newer variations a distant old relative to the current generation. With little effort anyone can relate to their distant older relatives, but it would be inconceivable that they would be convinced to live like the earlier generation.
Defined with the value system having roots in a contractually handled market system, all the relationships would be between non-life abstract entities like organizations but not people.
"CMMI for Development, Version 1.2".  recognizes people amongst the three critical dimensions of an organization. But it emphasizes that it is the processes that hold the other two. Since the technologies are changing quickly and people are regularly changing jobs, CMMi believes to entrust more on processes that can be made static and can address the other two