I asked an old associate who has been doing algorithmic trading (using his own money and doing quite well at it) about this and he told me that when he attempted to offer his algorithm's recommendations to investors he discovered the SEC has cracked down on any form of stock recommendation business to the point that, practically speaking, you need a fund of tens of millions of dollars to make it profitable.
This may help explain the abandonment of this business area by Quantopian.
