"The main culprit is SOLID's focus on dependencies. "
"These all lead developers to create interfaces everywhere. They litter the codebase with interfaces like IFooer, IDoer, IMooer, and IPooer. Navigating it becomes a nightmare. "
http://qualityisspeed.blogspot.nl/2014/08/why-i-dont-teach-solid.html
Personal experience:
I ever worked on a similar project: this project has two functions: a wrapper for Icewarp API to create/update email accounts.
3k line of codes, near 10 layers of interface. Indeed, it is "SOLID" :)
