Reading "Broken Markets" by Arnuk and Saluzzi, one learns that the problems lies also in the presence of High Frequency Trading algorythms, preying on institutional investors order flows. Some dark pool also sell information to HFT firms, some brokerage firms sell off-the-shelf- algorythms to their institutional clients, so that they can predict their clients trading patterns. Arnuk and Saluzzi's account of the "industry" rapid change suggests there are deeper forces at play (p.74):
Demutualization changed the ownership of the exchanges from a member-owned, nonprofut organization to a shareholder-owned, for-profit corporation. What was once thought of as a quasi-government utility-type organization would now be a bottom-line driven publicy traded, shareholder-focused company. The old method of having members vote on proposals and rule changes would be abolished. Exchanges would now make decisions by executives who reported to the board of directors who served the shareholders. Unfortunately, as we have seen all too often, shareholder interests and investor interests are not always the same.