I see this as a design choice - works as designed and functioning as built situation. All engineering and hardware design is an exercise in tradeoffs and many of the goals compete against each other:
- reliability of the parts as they age
- ability of manufacturing to make the device reliably and repeatably
- cost of parts
- cost of manufacture
- speed to diagnose and repair
- durability of repair (nothing makes us mad like looping repairs when the issue isn't fixed or more issues are caused by a repair for something else)
I haven't even got into the more relevant design decisions like which CPU chip to put it and whether the higher CPU model gets the same power supply and battery as the lowest performing CPU model. Or whether the CPU you chose can out run the power supply since the battery can and has always for the last 10 years been able to supply far more current on demand than the charge rate of the battery from the AC power supply transformer. The only intel based Mac product that can't outspend their power supply are ones that plug into mains. No portable Mac can keep up with a fully running CPU/GPU when cooling is good enough to keep thermal throttling from kicking in.
I'm not at all saying you are wrong to be irritated, just that this was a conscious decision made by teams of people knowing some times their design won't keep up and then management trusting / approving those design decisions and shipping years of product with that decision. When viewed from the lens of CPU shouldn't outpace the power supply, this is a compromise. When viewed from other lenses (lightness, parts management, reliability, supply chain management), this is an excellent/beneficial decision (or still compromise). I hope this helps you know you're not wrong and that this would be something you consider when you choose how your processing load gets run. Whether you can offload some tasks to the cloud or if you need to be tied to mains power since you can't accept this sort of tradeoff for your needs.
