Insignificant revenue. The click-through rate might very well be so low that only a small amount of revenue would be brought in by the ads. It would not be worth barraging thousands of readers with ads for only a few pennies of revenue.
Ads cheapen the encyclopedia. By their very nature, ads are biased content intended to influence people. They are thus diametrically opposed to the goals of a neutral encyclopedia intended to inform people. They would cheapen the encyclopedia in the eyes of many readers, as evidenced by the numerous anti-ad comments received during every donation drive.
Contributors may leave. Many contributors vigorously oppose ads (see the forking of the Spanish Wikipedia, 1, 2, 3, 4), and in 2009 the Wikimedia Foundation promised to keep "Wikipedia. Ad-free forever." Since about 2002, Jimbo Wales has repeatedly stated that he opposes all advertising on Wikipedia as well. Based on these statements, some editors have probably contributed with the understanding that their content would not be diluted with ads. Changing the long-standing no-ads policy now could reasonably be perceived as a bait and switch tactic. Numerous contributors are likely to leave as a result and new ones are less likely to start. Contributor goodwill is Wikipedia's main asset and should not be gambled with.
Annoying and distracting. Readers come to us for encyclopedic information, not for ads. Ads have to be processed by the brain (if only subconsciously) and therefore distract and annoy. "The free encyclopedia" also means: free from distractions and annoyances.
Privacy violation. If an ad consolidator such as Google AdSense is used, the privacy of our readers is compromised. The consolidator will invariably learn which Wikipedia articles a given IP address reads or searches for; they can then correlate that information with other data they may have about that IP address (e.g. Gmail account).
He copied and pasted from a Wikipedia page, so I spent as much time crafting my response as he did. More importantly, those arguments are so blatantly wrong on their surface that I don't believe they justify more than a one word response.
Insignificant revenue. The click-through rate might very well be so low that only a small amount of revenue would be brought in by the ads. It would not be worth barraging thousands of readers with ads for only a few pennies of revenue.
Ads cheapen the encyclopedia. By their very nature, ads are biased content intended to influence people. They are thus diametrically opposed to the goals of a neutral encyclopedia intended to inform people. They would cheapen the encyclopedia in the eyes of many readers, as evidenced by the numerous anti-ad comments received during every donation drive.
Contributors may leave. Many contributors vigorously oppose ads (see the forking of the Spanish Wikipedia, 1, 2, 3, 4), and in 2009 the Wikimedia Foundation promised to keep "Wikipedia. Ad-free forever." Since about 2002, Jimbo Wales has repeatedly stated that he opposes all advertising on Wikipedia as well. Based on these statements, some editors have probably contributed with the understanding that their content would not be diluted with ads. Changing the long-standing no-ads policy now could reasonably be perceived as a bait and switch tactic. Numerous contributors are likely to leave as a result and new ones are less likely to start. Contributor goodwill is Wikipedia's main asset and should not be gambled with.
Annoying and distracting. Readers come to us for encyclopedic information, not for ads. Ads have to be processed by the brain (if only subconsciously) and therefore distract and annoy. "The free encyclopedia" also means: free from distractions and annoyances.
Privacy violation. If an ad consolidator such as Google AdSense is used, the privacy of our readers is compromised. The consolidator will invariably learn which Wikipedia articles a given IP address reads or searches for; they can then correlate that information with other data they may have about that IP address (e.g. Gmail account).
et cetera et cetera et cetera.