The point is total capacity, of course if you hit max capacity all day you can move more people, but as 9-5 commuting is likely slowly dying after pandemic this matter much more.
Montreal just unveiled the first Alstom Metropolis train that will be used on the REM, and I got the chance to check them out in person! Enjoy this first hand look.
https://youtu.be/tmPXUmV822U