More than reputation, it’s one’s stay on the forum, once he is actually discovered, which could even be months or years down the road to the plagiarist’s dismay.

They tend to plagiarize in order to cut corners for one reason or another. Most will likely do it deliberately in order to pass the text as theirs, possibly not aware of the penalty on the forum, but likely with the said intent. There may be others that post something believing that they are being informative, not being aware thay they need to cite the source here.

Perhaps though, there is wiggle room to make it manifestly clear, by including a clear reminder when creating a new post (something along the line of what is mentioned in rule 33 + the example, and emphasizing on referencing the source). This has been commented before on multiple occasions, is seemingly easy to do, and shows some good will to trim the number of cases we recurrently see. Nobody would be able to claim ignorance from there on, which is what we often read.