But the entire point of this system is to make sure, that the top stake holders don't have as much influence on the top 20 witnesses.

That isn't at all what the entire point of the system is.

Especially since witnesses 1-20 have the power to make all the decisions in relation to hard forks etc.
With >= 20 votes, pumpkin has an enormous influence in this. If we reduce this to <= 10, this helps a lot.

It does not help a lot, it probably doesn't help anything at all, why would it anyway, you're asking for large stakeholders to split up their stake after all, like I said, why not limit it to one witness vote, it accomplishes exactly the same thing.

And I agree, this can be further reduced, to 5,3,1. But I think 10 is a good number. 10 allows people to select a number of witnesses which represent them well and they think represent Steem well while not giving anyone enough power to have such a huge influence in selecting ALL top 20 witnesses basically alone.

Like that post I linked, it's hardly the case. I don't think we should encourage people to split their stake up, I think that this suggestion fixes absolutely nothing and I wish you good luck to get the large stakeholders to undermine their power because of notions that "they have absolute power" or anything to that effect, especially when it's neither the case nor was it ever intended for this to be one witness one vote (which is where you want this to end up), it was intended actually to give people with more stake exponentially more power, after all, if you don't trust the large stakeholders to safeguard their investment it makes no sense to trust a bunch of small stakeholders to do the same.