First off, I will say that yes, M1 chipsets are much more power efficient than intel based chips. However, this does not make intel based laptops "laptops that should not have been laptops", as evidenced by Apple (and everyone else) producing them for well over a decade.

1) Even with the thermal dissipation a M1 macbook has, a desktop could cool a M1 better. There's simply more room for a larger heatsink with more surface area, and fans that don't have to throttle, than a laptop format could ever provide And with the coming M1 desktops, we will see this in action.

2) The M1 MacBook Pro has a measured draw of ~120 watts under load (measured by anandtech; there's still the GPU to power, despite the better performance of the M1 itself). Apple power supplies, until recently, topped out at around 90 watts.

Here's where Apple's slightly ahead of the game - they're using the updated PD specs in their latest chargers to get a 140 watts out over USB-C, and packing them with the new 16" macbook pros (though not the 14", they're still topping out at 67/94 watts).

So the outlook for M1's in terms of power is better than average, so long as you pay the Apple tax. Worth it? Perhaps. Perfect? Not yet.