I won't mind criticism but it should have some weight to it.
1. First Hagoromo level op. That's absolutely false. He isn't even close to Madara and hashirama level until the age of 18 much less Hagoromo. Let me make it clear having an affinity for every element doesn't mean mastery. Having tail beast level chakra doesn't mean chakra control, having healing factor doesn't mean he is invulnerable.
2. Second for the Uchiha Massacre part. People asked me to conduct a poll. So I did it. It is reader's choice.
3. Third part about following canon, sure I tried to deviate from the canon with the idea of Sin seal. I got a huge community backlash. People accusing me of ruining Naruto despite knowing it is a fan-fic and a free book. I was a new writer back then and thus easily gave up to peer pressure since reader's satisfaction was my priority. I have learnt my lesson and now I am writing what I want to write not what people want to read.
Part of the reason there are no polls or anything of that sort.
4. OC doesn't make any sense and he won't for a while as I will slowly put back all of the pieces together. You can't make a painting without outline and outline isn't always the best.
I admit I made lots of mistake but I am in a phase of learning and as I improve I will incorporate my mistakes into the plot to make it more interesting. Yes, it would be challenge for me to make my drunk writing into something interesting but I like to take challenges.
5. Train Naruto and Sasuke. Well of course, he will. Sasuke is his family and Minato and Kushina are his teachers. He won't be a human if he can't repay his favours.
6. I know people want to focus on main character and main character only but his presence influence other characters and their development. Some light must be shed on that too otherwise the story will be an empty vessel where the MC moves around messing with everyone with no repercussions.
I hope this shed some light on what kind of fan-fic this. As we move further in the story, there will be so many elements which will be incorporated in the story.
As for the shallow knowledge of Naruto world, I won't brag anything but till now everything is a part of Naruto world and I will write it such a way that even Sin seal will become a part of it and when it does I am sure people won't be able to deny the possibility.
P.S. It's not for any hater or of that sort. Since they are also a part of community. Love and hate goes side by side. You can't love everything and take writer's word for everything and also you can't hate everything since there will be some moments where now matter what you enjoy it. Be it humour, a battle or anything of that sort.
Also, the word haters is overused. I have moved past it. For me a hater is a person who just had a bad day and he read something which didn't interest him.