why do sellers change asking price to sold after a sale?

[Oscar_Stanage]

I will chime in here as this is something I do.. here is my rationale:

At first, I had no idea how to sell a card, so I just did it because everyone else does.

now I continue for the following reasons.
1) it makes it clear the card is sold. I have left prices up (and note sold in the message) and continue to get messages on cards.

2) It protects the buyer from others knowing who bought it. If someone sends a "PM sent" message and the card is sold shortly thereafter, it can be known who bought the card and at what price.

3) Sometimes I may take a lower price and do not want that to be the base case assumption for other cards in the listing

There are definitely ways to accomplish all of these and also leave the sale price, but I just find this easier and preferable for me. I am not sure why this would annoy anyone.

I am annoyed by the unwritten rule that no one can comment on on a seller's cards/prices. IMO there is a nefarious/dishonest intent behind this, but I abide by it.