In this question, How to withdraw an under review manuscript from a journal when you decide you want to submit to another journal with a higher impact factor?, the asker is told pretty clearly—in multiple ways—that it's totally unacceptable to withdraw your paper for this reason. Indeed, some might think the answer apparent, but the OP obviously didn't, and came to the Academia Stack Exchange to seek some help.
One of the responses' fist paragraph was the following:
Editors are reading these sites too. Like me and the editor who posted this link on a large editor list serve I'm included in. I'll be keeping an eye out for your papers (as will they) and save you the trouble of wasting me and my reviewers' time by desk rejecting your papers as they come in.
Is this type of thing... allowed?
If so, why? I think this sets a pretty crappy precedent.
(There are also some good points mentioned in the comments to that response that I won't replicate here; I flagged the post, but will [reluctantly!] unflag it if the consensus is that this is allowed, and ok.)