Frankly, I would consider the OPs argument more valid if people in this game actually took the time to help new or inexperienced players improve. So many people using the duty roulette treat it like a loot pinata and harass the newbies. I've just started gearing/using my PLD in high level dungeons and the amount of flack I take is ridiculous. I never had to deal with such rude people as a DPS, even when I made obvious DPS mistakes like eating too many AOEs and straining the healer.

Today I spent over an hour coaching and being coached (as a first time tanker) through Pharos Sirius. Did we clear it? No. But by the time we abandoned the duty both me and another DPS were much improved at our respective jobs. Before you start talking about 'mediocre' players leeching off of the work of pros, take a look at how you play the game and whether you're contributing to other's experience or simply harassing them and making everything worse. If you're not going to take the time to help others improve, you have no standing to criticize bad players. It's one thing if you're attempting to be helpful and people shut you down. However, the majority of the time if you mention something politely players will respond in kind.