Earlier quoted context omitted.
I don't think I've ever seen that behavior with a MacBook Pro of any vintage -- and I've had an MBP of one stripe or another since at least 2007, using the date of the 2007 MacBook Pro gathering dust bunnies nearby -- except when I use the wrong power supply with it, e.g., a 13" MBP power supply with a 15" one, or my MacBook Air's power supply with any MBP now. I wouldn't doubt it's possible to draw more power than t…
Try mining cryptocurrency, running prime95, playing fps shooters, or even dota on high settings. You will notice the battery draining while plugged in. You also see it if you are on an airplane, but that is usually because the charger tries to pull too much and overheats and gives up ghost. Macbooks have underpowered chargers.
My 16” shipped with a 96 watt charger, and I’ve not seen a laptop with a higher powered one. I’d have to contend with that assertion.