Every independent economist has been saying this for the last 10 years- see for example "Capital in the Twenty-First Century", a book written by French economist Thomas Piketty.
Claiming that even a majority or plurality of economists overall agree with Piketty, who advocates for some wildly unpopular economic policies and is a literal socialist, is absurd, so your group of "independent economists" must be pretty homogeneous and small.
When even Adam Smith supports the regulation of capital, this can be considered a fairly mainstream position.
I can point to dozens upon dozens of independent economists (by your definition) that disagree with the use of confiscatory income tax rates and wealth taxes, so I don't know what your argument is here.