It does not support LPDDR4... which is something Apple has been targeting because it uses less power.
The rated battery life of the Macbook Pro didn't change between 2017 and 2018.
I find myself scrambling for a power supply way more often than I ever did with my 2017 15" MacBook Pro.
Even with the older battery in the 2017, with more cycles, I get a longer battery life out of it than the 2019.