They speak of NV humans as being inferior, yet they've proven that their own selves are on the lower end of things both intellectually and physically. Kaguya had visible issues, Toneri.. didn't watch, and Momoshiki thought it'd be a good idea to attack Naruto and Sasuke before absorbing others. All got chewed out in the end and even non-Rikudo tier fighters(Sakura, Gai, kages) can compete with them.
Now, what isn't making sense is why. If these guys have been harvesting chakra fruits and living for thousands of years, they and their children should be haxxxx. How come roughly two halves of Hagoromo is enough to stomp them out? Even BZ suffers from this, he should be a God that knows everything.
Sorry, but your post is just wrong.
1. First of all, of course Kaguya had visible mental issues. She spent thousands of years sealed inside the moon! I doubt that anyone would come out the same after that. Not only that, but her sons were the ones to seal her! She must have been heart broken about this. She even cried about this during her fight with Naruto and Sasuke. Wouldn't you feel betrayed or upset if your kids sealed you into the moon for millennia? Long story short, Kaguya by no means showed herself to be stupid or intellectually inadequate. She just had very unique circumstances that would affect anyone at least to some extent.
The closest thing to stupidity that Kaguya actually showed was getting tricked by Naruto passing his truth seeking balls onto his clone, but this more so just shows that Kaguya isn't the most battle smart. However, battle smarts and general smarts are two very different things (just look at Goku for crying out loud who is an absolute battle genius, but in other intellectual areas is pretty slow). Plus, who is to say that Kaguya was even a fighter to begin with?
In fact, who is to say that any of these Otsutsukis are fighters to begin with? As far as we know right now, these aliens are more so intergalactic farmers than they are fighters. They go from planet to planet expecting it to be a simple task to harvest chakara fruits. They don't expect to encounter powerful opponents (especially not rikudou level ones), and they are probably not experienced enough in combat to be prepared for such opponents. If you ask Momoshiki, the likes of Hagoromo, Hamura, Naruto and Sasuke were never even supposed to exist! Kaguya was just supposed to go get the fruit and bring it back home!
2. As for your "Toneri... didn't watch" statement, that is simply your fault. You should watch something to know about it before degrading it. I hate it when people say "didn't watch" or "didn't read" and then treat that as validation of their point. If anything, your ignorance about the aspect that you didn't watch/read takes away validity from your point since that means that you are less informed about the overall topic than someone who did watch/read.
3. About the "Momoshiki thought it'd be a good idea to attack Naruto and Sasuke before absorbing others" point: That is more so arrogance than intellectual stupidity.
4. @1st Bold: That is a lie! The only Otsutsuki that non-rikudou characters can compete with is Kinshiki (the weakest known Otsutsuki) and even for him it took 4 kages. You speak as if he got easily solo'd.
5. @2nd Bold: You seem to forget that the fruits have levels to them. Kaguya's was a level 16 fruit, and Kinshiki implied that fruits over level 10 are so rare that need to be reported to the clan head. Since Kaguya ate such a powerful fruit, it makes sense that her sons would inherit tremendous power. Also, let's not forget that Naruto and Sasuke didn't stomp them out as you say.
You speak as if these Otsutsukis got absolutely wrecked with no difficulty. However, Kaguya had the chance to kill them so many times! The only reason why she didn't is because at first she was focused on taking their chakara rather than killing them. Then, when she decided to kill them, she actually was about to succeed in this. Naruto and Sasuke would have been dead if Obito (and to a lesser extent Kakashi) didn't save them. All in all, it took 2 rikudou level transmigrants, a sanin level kunoichi, an additional Uchiha with an amazing mangekyou sharingan ability (kamui) and rikudou chakara, and later that Uchiha's friend (who was temporarily given said MS eyes and rikudou chakara) to beat her! Even then, they couldn't kill her. They had to seal her.
Naruto and Sasuke wouldn't have stood a chance against Kaguya by themselves. As for Momoshiki, he actually had Naruto, Sasuke and all the other kages in prime position to kill them! He just wasn't expecting Boruto's vanishing rasengan. Let's also not forget the fact that it took both Naruto and Sasuke (not a 1 vs 1). Individually, Momoshiki already captured Naruto earlier, and during the fight, he critically burned Sasuke (causing Naruto to have to heal him).
So no these guys didn't just get stomped out!