Yay, one of my favorite topics
I've been enjoying the reef hobby for over 3 decades (saltwater for 4) and have rarely used a skimmer, GAC, etc. My last 55g ran nearly 10 years before I took it down. I currently run a 12g mixed reef cube which has been in continual operation for over 8 years using the same 'natural filtration' principles.
The stability inherent in these 'simple' systems is what makes them so long lived, in my opinion.