A lot of assumptions wrapped up in such statements - one of which is the one you found: Batteries are typically among the first components to die.
2) My M1 MacBook begs to differ again
I feel like you are talking about laptops that should not have been laptops in the first place here
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.
- A laptop will never have greater compute power and heat dissipation than a similar tier desktop.
- Current laptop models will often consume more power than can be provided by their included power supplies (one culprit is USB-C's 100 watt limit, the other is simply cost). Thus, their compute endurance is hampered by the battery. I see this when merely running Google Meet.