It all depends on you nutrient import /export balance and the age/maturity of the tank and if it can reach a natural equilibrium that's also pleasing to your eye.
For ex- if you leave a young tank alone without any help for nutrient export, you'd reach an equilibrium that probsbly consists of a forest of hair algae and that obviously make the tank ugly
However an old tank can reach equilibrium by have huge coral colonies and a diverse base of microfauna that will absorb majority of the nutrient, algae will still be present but will be kept in check physically by limiting where they can grow (bc all of your rock is covered by coral), and be CuC elimination. In those systems external/artifical nutrient export is not as critical needed.
i have a 7 year old tank - I use skimmer now only for aeration and have stopped really monitoring nitrate and po4 and just let nature do its thing. No other form of filtration.
Heavily stocked coral colonies, a lot of diverse cuc, and not too heavy fish load (2 clown, 1 coral beauty, 1 canary blenny)
Minimal algae on rock bc its almost entirely covered by coral or coraline, tho I do have to scrape the glass every week since thats the only place algae can take foot
I use apex to monitor the big ticket items and autodose 2part, then I do a large water change every 3 months to replace trace elements and "reset" the water so it doesn't drift too far from whatever anything that's accumulating that we are not actively monitoring.
But, in my tanks younger days, you can bet your bottom dollar that I used every form of filtration one time or another - skimmer, fuge, socks, roller, etc..
