Depending upon the Intel CPU, 16GB might be the maximum it can support without using a more power hungry type of RAM. Certainly this was the reason MacBook Pros were limited to 16GB until the last refresh, at which point Apple gave up waiting for Intel and decided to allow customers to take a hit on the power consumption.
And yeah, as you note, there are real Mobile Workststion-class Think Pads available that can't be realistically used too far from a plug socket. RIP the crazy W series with pull-out secondary screen and integrated Wacom digitiser - you were just too strange for this world.