Over the short-term people adding WoM and bringing the book into line with other bookmakers is welcome, because it means the market is becoming more efficient.

Over the short-term people adding WoM and bringing the book into line with other bookmakers is welcome, because it means the market is becoming more efficient. At the micro level then, turnover is welcome. But as the old adage goes "turnover is vanity, profit is sanity" At the macro level somebody has to say "how do we maximise profits or at least minimise losses?" and picking off accounts that are costing you money is an easy step to take. The ideal client for a bookmaker is an idiot with a strong view. They don't want people who will consistently win, because it's taking up WoM for other customers who could be invited with those more generous odds and who _don't_ consistently win.