On Thursday, 8 August 2013 at 19:15:29 UTC, Walter Bright wrote:
Under Extension Methods, a huge reason for them is to head off
the temptation to write 'kitchen sink' classes that are filled
with every conceivable method. The desired approach is to have
the class implement the bare minimum of functionality, and add
other functionality with extension methods (that do not have
access to the class' private state).
http://www.drdobbs.com/cpp/how-non-member-functions-improve-encapsu/184401197#.UW1X9HWZeXA.reddit
I think you linked this Meyers article at some point as being the
original rationale for UFCS (correct me if I'm wrong).