I believe folks already understand whether or not the pricing is appropriate or whether the seller is trying to make a profit. If someone thinks they can detract buyers by mentioning such reasons for sale then they are sadly mistaken. The reason for sale does, however, give an indication of transparency and honesty.It's a good thing that it doesn't matter to you whether it is a reseller or not. However, then it also shouldn't matter what reason one gives for sale. Just my opinion, but adding a reason for sale adds nothing of value to the actual sale. Like you have pointed out yourself, it's the selling price and whether there are buyers for that price, that is the most important factor. Nobody ever raises such hue and cry when things are being sold for cheaper.
As for people writing other reasons, it's very simple. It's to detract buyers who would bargain just because they think you are making a profit. This happens on OLX as well BTW, because people bargain a lot harder when they think you are a dealer. I am someone who doesn't know how to bargain, so I used to stupidly quote my final price when selling, even on OLX. Plus I get flustered very easily by people who bargain as well. Learnt it the hard way that one has to quote a higher price initially because most of our 'janta' doesn't know how to buy without haggling, but it still didn't sit well with me.
In the end, all I want to say is that it's better to have the marketplace running as simple as it can (apart from legal issues that had been raised and necessary steps taken) and not bring unnecessary complexities. It only hampers the experience for both buyers and sellers and many sellers leave for other avenues then. We have had a well running system for such
The buyers will almost always try to bargain irrespective of the reason for sale and there would be lowballers as well. You can always just ignore them (like I have done umpteen times and it's pretty effective) but if they are creating "nonsense" simply report them.
I, for one, don't see the TE Marketplace as another Olx but view it more as an additional service for members to offload stuff that they are not using or don't intend to use. Resellers and dealers definitely have their place and are welcome to participate as long as they stick to the guidelines and have the Mod's blessings.