Magnetic Hotel Key Cards

There was a circulation lately, that the hotel key cards contain guests' personal information including credit card details. In that circulation, it asks all hotel guests not to return the key cards, and destroy it at home.

Recently my office also received this circulation. After the security department researched further, it is confirmed that it is a hoax. You may want to read the detail here.

However, as pointed out in the site, though all major hotels do not practise encoding these sensitive information on the hotel key cards as it is not necessary, the point to ponder is:

IT IS TECHNICALLY POSSIBLE TO DO SO

Therefore, to reduce the risk, if I am not staying in major hotels, I would destroy the keys at home. What about you?