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The concept of evolution stones was that you get a strong pokemon right away, but it won't learn anything good unless you use TMs. Short term powerspike. Then GF lost the point of this entirely in gen 2+ when evolution stones became more often than not a rare lategame item
It was an interesting concept at first, but the games have so much selection available now, with many other strong early options, that power spikes are common just by playing the game normally