I think you missed his point. No one is saying that amanita is perfectly safe. It isn't, amanita can shred your mind to pieces especially if you don't respect it or don't know what you're doing. It can also cause more dangerous physical effects than psilocybin mushrooms or mescaline cactus tend to, although it's toxicity tends to be overstated and deaths from amanita alone are very rare and usually involve mistaken identity.
The significance of the thousands of years of history is that is gives us a knowledge base to build off. For example, alcohol has thousands of years of history of usage and is one of the most well studied drugs. Does that mean alcohol is perfectly safe? Of course not, but we know what the risks are. That's why I'd feel much safer consuming alcohol compared with some new alcohol substitute that just got invented last year.
The same is true for amanita, we know that it has a long history of successful use without killing or maiming too many people and many people report high levels of value from it so why wouldn't it make sense to investigate its healing potential?
As for last question, I don't see any reason why to not investigate it. I'm stating so might be true for ibotenic acid. Kind of like why would I use MK-something that's a proven neurotoxin to induce NMDA antagonist high while there are neuroprotective NDMA anatagonists or at least likely not neurotoxic.
If we gona talk about traditional use I've heard for and read about many traditional and supposedly traditional ways of Amanita preparation that convert ibotenic acid to muscimol. If ibotenic acid was that great I guess traditional way would be simply eating them raw or doing extraction that doesn't convert it to muscimol.
Sun drying, fire drying, teas, alcohol infusions, drinking piss all usually to some extent convert ibotenic acid to muscimol.
Even if it's a thing similar to how ayahuasceros recommend fasting before aya, yet it seems strict diet isn't really needed. Well eat some spoiled food with MAOi and you'll figure out why it's done.
Compare that to benzos, which don't have thousands of years of history of use and have already been shown to do terrible things to large numbers of their users. I would be shocked if people are still using benzos thousands of years from now.
If rotten fruit created etizolam instead ethanol we would.
Benzos vs. Booze? That's a really though one. I vote booze cuz it's food too and can be very tasty.
It does say something and it is somewhat of a mystery how the knowledge of amanita and its uses was lost to history outside of a handful of countries but that's a whole other topic to speculate on and I'd argue it's not that uncommon in the world of psychoactive plants. Take kava for example, it's an incredible herb with lots of recreational potential and a great safety profile but it's not really popular except in a few countries. Even substances like marijuana and opium, historically speaking there were many cultures that were aware of their existence but did not really use them very much. How do you explain that? Prior to 20th century I don't think cannabis was used much in the USA despite it's existence being known about it and it being entirely legal.
Opium and opium tea was and often still is used as medicine in many countries where domestic poppies were introduced and can grow.
Cannabis wasn't that interesting outside places where growing potent enough stuff and than converting it to hashish wasn't viable. Also cannabis orally if not prepared right isn't psychoactive. And smoking it if it's not potent enough, and it's really hard to find landrace growing wild that's nearly potent enough, will definitely seem less tempting than smoking some tobacco. While tobacco can easily be too potent if smoked as it is. And poppy tea with very small amount of poppies can provide strong pain-relief and other medicinal effects.
Amanitas ain't hard to find at all. They are very widespread and very easy to find and identify. Plus they if you consume ibotenic acid don't require any preparation. If you go by some of most walked forest trails in my county you can't miss them. I'm sure it's similar at countless woods all over the world. That people all over the world "forgot" it's used as a drug seems so weird. More so that it didn't gain popularity during 60s and 70s when some arguably very shitty drugs did.