Guilds etc evolved on their own as power-structures, parallell to governements. Unregulated free markets always create monopolies, or if you prefer concentrates ownership on so few hands that said hands have what functionally amounts to monopoly. It's an inherent function of accumulation of wealth beyond the needs of the household. Blackrock ring a bell? If you prefer a historical example, how about Marcus Licinius Crassus? You are wrong about "...having, say, 3-4 big companies competing in a space drives prices down and quality up...". It does the opposite. What always happen is those 3-4 actors will co-operate and keep competition to an absolute nominal minimum so as not to hurt their own bottom line and profit margin for their owners, and this will happen without any open official collusion on their part: a tacit gentlemen's agreement is enough. The food and grocery market in Sweden is the prime example: three corporations control 85% of the entire market, from raw goods to refined products, imports and stores. Prices vary less than 5% between them on average, despite the mark-up for some goods being in the hundreds of percents. What's left of the "free market" is Lidl (about 10%, stores level only) and privately owned corner stores selling sodas, candy, chips, tobacco and such.