If you don’t think defensive security is “real” security work, then you’re using a definition that very few people use.
an analogy:
The school nurse putting a band-aid on your knee is "real" medical work, but that same nurse has no place in spinal surgery operating room.
The school nurse is every "certified ethical hacker" and "certified cybersecurity expert". The spinal surgeon is the reverse engineer. We need nurses, but we also need spinal surgeons more. Every spinal surgeon can practice as a school nurse, but (perhaps) 0.1% of school nurses can practice as a spinal surgeon.