Member Artists are not permitted to PM requestors, asking to "take a crack" at a request. It is no different from filling the request when it's in the wrong section, ergo, it is against the rules. In some ways, it's actually worse than filling the request outright because you're doing it behind the backs of the moderators, hiding your name so that you cannot be caught in the act.
While it is clearly understandable that many Member Artists are enthusiastic to take requests, getting practice and getting their work out there. There are more Member Artists than there are requests to fill them, so why not let you all fill all the requests you want?
Answer: quality of TDA work. The most important aspect of promoting an artist from Member to Junior is "whether they are capable of filling requests" - this means capable of making technically solid and aesthetically pleasing graphics. Member Artists are those who may be close to this point, but are not there yet. To allow all artists equal capability of filling requests would lower the standard of quality as well as the overall reputation of this site's artists.
Never PM requestors asking to take their requests. If you do, you will be given a 10% warning. Do it again, you will lose your artist title and not be put on the promotion list for two months.
The request referred to in the quote above will not be moved, even though it means frustrating the requestor. Please do not put me in this position again.