You are right. The effectiveness of the Keys depends on how well the decoding algorithms are incorporated into the software of the receivers. These days, most of the providers are switching to more robust methods of encryption that are hard to h*ck. Many are using auto-update facility where the keys keep changing constantly and a legitimate receiver (or properly h*cked) receive them over satellite.
By the way, not all keys posted in this forum look like latest ones. Look into some upload sites. You will find updated keys being posted everyday, sometimes multiple times in a day. Only a dedicted hobbyist devoting full time can keep track of them.