It is more than a decade now that no human has beaten a top chess program, and now there are computer vs computer matches continuously running and getting results. Those results are used by programmers to improve the algorithms. The improvement is not merely a result of the increasing CPU speed, but also the result of theory research and improvement in the algorithms that prune and evaluate the game tree. This process was driven in the 80s and partly in the 90s by the desire to make the programs stronger against humans, but beyond a certain point the programs became so strong that now they are only tested against each other (and even against themselves) and I wonder if that is causing a deviation from chess into... another thing.
Hence my question. When top chess programs fight against each other at a level that no human could withstand, evaluating branches of the game tree up to an insane depth, how do we know that, beyond a certain depth, the moves make sense?
Let me explain my question with a simplified example. I bought recently a table chess computer in a toy shop chain, and it plays really bad. Even set at 3 minutes per move, I honestly doubt it is reaching farther than 1 or 2 plies at most and I am sure it is without any check extensions. It is really easy to beat, it goes out of the opening book at the 2nd or 3rd move, and it blunders miserably all the time. However, if you force it to play against itself, it stays within the opening book quite long, you don't see obvious blunders and the resulting game does not look bad. The algorithm playing against the same algorithm produces something that seems like decent chess, but I know it is fake, because if I interrupt it at any point and play against the machine I will beat it in no time. Hence my doubt when this example is translated to a much higher level... Do the strongest human see any value on those Stockfish-Houdini matches, do they give credibility to what those machines play, or it is simply crap nobody understands?