Because batteries have a very high current output. Matching a high end battery tool with a power supply is quite simply not really reasonable. Something like a circular saw or angle grinder probably peaks out at about 600-800 W, or something like 40 Amps at 20 V. That’s one hell of a power supply. I’d expect such a power supply to be at least a $100-200 thing. Few would think that’s a reasonable price for what it does, so it wouldn’t be a profitable product.
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