It evokes the "real engineers don't use it" reaction, similar to any tool that's perceived as being of primary interest to hobbyists and students.
Some concerns are valid: Arduino doesn't have as much flexibility for digging really deep into things like pin and memory assignments and what happens when a microcontroller starts up. Also, the quality and documentation of Arduino support can vary from one MCU family to another.
There's a concern about the quality of libraries and code.
It doesn't support hardware debugging.
Granted, the embedded community has good reasons for being conservative, especially for critical applications.
Some concerns are valid: Arduino doesn't have as much flexibility for digging really deep into things like pin and memory assignments and what happens when a microcontroller starts up. Also, the quality and documentation of Arduino support can vary from one MCU family to another.
There's a concern about the quality of libraries and code.
It doesn't support hardware debugging.
Granted, the embedded community has good reasons for being conservative, especially for critical applications.