Top 10% owning 10% of wealth makes no sense as it means perfectly equal wealth redistribution. It is an ultimate goal, but it is not practically achievable. 20% is close enough.
It is an ultimate goal
it isn’t though. Wealth distribution isn’t the aim of communism, just inevitable effect of it. And as such it don’t have to be exactly equal. Quoting Lenin:
The abolition of classes means placing all citizens on an equal footing with regard to the means of production belonging to society as a whole. It means giving all citizens equal opportunities of working on the publicly-owned means of production, on the publicly-owned land, at the publicly-owned factories, and so forth.
In a higher phase of communist society, after the enslaving subordination of the individual to the division of labor, and therewith also the antithesis between mental and physical labor, has vanished; after labor has become not only a means of life but life’s prime want; after the productive forces have also increased with the all-around development of the individual, and all the springs of co-operative wealth flow more abundantly – only then can the narrow horizon of bourgeois right be crossed in its entirety and society inscribe on its banners: From each according to his ability, to each according to his needs!
As you can see total equality is neither achievable nor desirable under socialism and meaningless under communism.
