Well it aerates the water pretty much as much as a skimmer does, and takes out nitrates and phosphates faster than a fuge, but doesn't give pods a place to breed away from predators.
I do all 3, skimmer, fuge, and ats. Haven't done a water change in 10 months.
The skimmer takes out waste, proteins, and fats before they enter the nitrogen cycle, removing them all together, plus aerates. The fuge helps with ph swings because i run it at night, and gives pods a place to grow, as well as removes nitrates and phosphates. The scrubber helps stabilize ph too, but really shines at removing nitrates, and some phosphates, ammonia and nitrites.
If i turn off my skimmer for a coupla weeks my ats grows alot more alot faster, but if i turn off my ats my skimmer collects the same amount, fuge growth picks up a bit, and the need for water changes comes quicker.
One thing to look out for when using fuge and/or ats for nutrient control, is keeping a closer eye on magnesium levels because the macros consumes it.
Check out linky,
https://www.algaescrubbing.com/threads/algae-scrubber-basics.264/