It's not overlooking the benefits, quite the opposite - when you consider the supposed benefits of any kind of AOP system, they do not justify the costs or complexities involved.
Tell me, exactly how many cases were reported to the CDC last year of people swimming in a single family residential pool contracting
cryptosporidium parvii ? Here's a link -
Press releases, advisories, telebriefings, transcripts and archives.
www.cdc.gov
So that's 444 cases over 12 years, or about 37 cases per year and and 35% were traced to contaminated recreational water facilities. That's about 13 cases per year. But let's assume it's triple that value since this reporting likely only covers commercial facilities that are required to report such data. So what, maybe about 40 cases of crypto per year....
Now there are approximately 10.4 million residential pools in the USA, and so my chances of contracting crypto by some crude math is - 40/10,400,000 or about 3.8 in a million....
So, given how small that risk is, do you believe that the benefit of AOP in eliminating chlorine resistant microbes is worth the installation costs (hundreds to thousands of dollars) as well as the on-going maintenance expenses and time spent troubleshooting the systems when they go down as well as the detailed chemical balancing required to run a low chlorine pool?
Remember to that these units only treat water that flows through them and will only kill planktonic (free-floating) pathogens. Algae and bacteria that has become sessile forming mats and biofilms will be completely unaffected by an AOP system.
Another thing to consider is this - exactly how much chlorine is saved by pairing an AOP system with a low level of chlorine. Chlorine is one of the cheapest sanitizers available and so it would take decades in any realistic scenario for the offset expense of using low chlorine to pay for a AOP system.
If you think about this logically, then there really is no benefit to installing an AOP system except to the installer that makes the money off of it. A pool owner can easily run a residential swimming pool using nothing but chlorine chemistry and be perfectly safe.