The rule of not allowing giveaway was to prevent account farming? Or is there any other purpose? I don't know, however I think this rule should be changed or there should be separate board for posting altcoin giveaway. I don't see any need for not allowing this.
Based on some of the replies here, it's mainly to prevent abuse of those XYZ tokens of little to no value.
But I agree with you that alts such as ETH should be fine since that restriction set by theymos was made years back.