Austin, yes, indirectly they do lower ammonia by removing ammonium, and homeostasis being what it is, ammonia will covnert to ammonium to be removed by the plants, ... provided ammonium levels are not drastically high (very low pH you have nothing to worry about.
if you do have drastically low ph and plenty of ammonium, ... that's just a dangerous mix.
beaslbob, ... curiosity, ... how different is your setup from the walstad method, ... to me it sounds very similar although you've said more than i've red of her book (i've red none, and still know more about her method over how yours is different from it.)
you can reinvent the wheel but ... while you think you've come across something amazing everyone else is looking at you from the cars they've been driving for years wondering what you're talking about and why you think it's so special.
to a lesser extent remineralized top soil, ... except your substrate base isn't remineralized, it has to be processed so the plants can get access to the nutrients.
humus, already remineralized, so that step is skipped
organics (humus) also preform some AEC action (retaining negative anions in the substrate)
you have no clay in your substrate, that would preform CEC (retain positive cations) so these are left to float into the water column
you have high pH, a sign of a possibly saturated water column with nutrients that your substrate cannot retain.
a high PH also removes some very important nutrients from the water column, boron, magnesium, iron, phosphorous, ... it limits others zinc, copper.
just removes these from forms that are usable by plants, ... in some cases it may be temporary (like nitrogen - our ammonia/ammonium relation), ... other times it's rather permanent (iron to rust - and you better hope you have a very acidic substrate, or you'll always have an iron deficiency, ... something i recall you mentioned you have to continuously supplement.
rust (which is accumulating in yours) is not good in a tank.
other nutrients in high pH will combine with other nutrients in the water column, move themselves into an insoluble state and both fall out (being unavailable to plants) i think it's calcium bonds with phosphorus, ... while calcium wants to dissolve into the water column, this will remove phosphorus from your plant availability.
listening to you in this thread and other threads you are good at pointing out that you know very little about what is going on in your tanks other than you are not changing water and your plants are healthy (enough) and your basing it on your "beaslbob method" that looks eirily similar to the walstad method, that she goes into enough detail to understand the sciences of what is going on in her tanks, ... something you are unable to provide us with, ... you are clear that you are going on visual observations as deciding from those alone what is going on in your method and deciding you have a 'good' method others should use.
i do know our tanks, and keeping them going, are very flexible, one person put forward a substrate mix he had that used (not exaggerating) a compost mix that included his dogs poop. and shrimp & plants thrived within days
our tanks are flexible, so flexible it's almost impossible to break them, ... yet you've got a pH high enough to ensure zero iron availability for your plants, ... you broke something in a near bullet-proof design and you're promoting it as good that everyone should try.
you've got a pH high enough in your tanks it's a wonder your fish are not stressed, ... but i haven't seen any pictures of your tank that show how vigorous and healthy your fish are, most freshwater fish i have seen like pH levels much lower than 8.0
6.0-7.0 are great, primarily as they're great for plants, (right nutrient availaibilty that years of evolution has decided is optimal due to nutrient availability) and plants that do a lot to make life possible for our fish prefer this pH range to grow it, ... and fish getting used to this level, again, due to years of evolution.
your pH is kinda scary high for most fish.
yet, once again, so long as things are stable we are seeing that things are, or can be a near bullet-proof design.
but how happy are your fish, how happy are your plants ?
you've got a theory, you're going on visual evidence and promoting a system that you are seeing is showing nutrient deficiencies.