The last time OPEC met, its decision to leave output unchanged cast doubt on the group’s relevance. That was a little premature. From the ministers’ market-moving comments to the array of oil executives gathered in Vienna to court new ventures, the Organization of Petroleum Exporting Countries showed no loss of stature in the run-up to Friday’s meeting, at which it again decided to maintain its current output target. While OPEC has ceded the role of adjusting supply to balance the market, its strategy of keeping up production is still driving prices lower now — and possibly higher later on. “Reports of their death are greatly exaggerated,” Harry Tchilinguirian, head of commodity markets strategy at BNP Paribas SA in London, said in an e-mail. “OPEC is still relevant because by driving down prices, and crowding out investment in higher-cost basins, they are sowing the seeds of the future price rally.” […]