To elaborate on my general sense of why the developers said that: there are now dozens of pertinent SDKs that developers need to stitch in to their apps. Same with APIs.

They take time to implement, can effect the performance of an app and sometimes don't really work all that well. An app developer could reasonably have dozens of third-party SDKs in an app. Say, Flurry, Applause Analytics, Google Analytics, Maps, Facebook, Twitter and so forth. Same with various APIs.

I remember one developer I was talking to on Twitter last year was so fed up with third-party SDKs that he basically swore them off except for the most essential ones. He was having a hard time stitching someone else's code into his app and the implementation was just wonky.