GPU have high latency. For a chess engine like stockfish which is designed to search as many positions as possible, the latency of a GPU is a big problem.
Engines like LC0 that do use the GPU work by searching fewer positions but with a heavier eval function. This makes the latency less relevant because it is a smaller percentage of the GPU time.
Engines like LC0 that do use the GPU work by searching fewer positions but with a heavier eval function. This makes the latency less relevant because it is a smaller percentage of the GPU time.