Unlike in most algorithms where correctness and performance are independent, chess engines can't be evaluated without testing performance at the same time; faster is not just faster, it changes the results.

So there is a tradeoff between the depth of the search and quality of evaluation. For traditional chess algorithms, better evaluation was rarely worth the cost; it would slow down the search so much that it didn't pay for itself.

But this performance tradeoff (like all optimizations) critically depends on hardware. Change the hardware and you change which optimizations are "worth it".

AlphaZero is clearly good at using TPU's to maximum effect. But what would its performance be in a CPU only environment? Maybe dumb but deeper searches still win there? This evaluation hasn't been done.

This isn't to say that the AlphaZero evaluation is "unfair". Rather that chess engines evolved to be too dependent on their environment. Getting maximum use out of CPU's is a strength, but not being able to use TPU's or even GPU's is a weakness.