Your own link explains how uncompetitive they are. Boeing's 737s range from 138-200+ passengers, the CS100 is in the 108-133 passenger range. More importantly t

Your own link explains how uncompetitive they are. Boeing's 737s range from 138-200+ passengers, the CS100 is in the 108-133 passenger range. More importantly the CS100 is significantly smaller and lighter, helping make it cheaper to operate on the routes Delta wanted. So to bid against Bombardier, Boeing didn't even try to offer 737s, knowing they can't fit Delta's needs. Instead they offered 717s and Embrauers, both of which are used (Boeing canceled the 717 over a decade ago).