Pretty sure that’s how super earth actually fights its wars.
For clarification, the Helldivers are not the regular earth military, that’s the SEAF. The helldivers are some sort of cannon fodder citizens high as fuck on propaganda, deployed on completely reckless complementary missions deep behind the actual front lines that have by default a low chance of success or survival and mostly only serve the role of cavalry: barge into the enemy supply lines, wreck shit and bail again, to take pressure of the main army.
As for the FTL (alcubierre) drive, according to the lore we encountered a third faction in hd1 that was initially peaceful but very technologically advanced, and essentially exterminated them and stole their tech. As far as I know the alcubierre drive model requires dark and/or anti matter to function, so I would guess humanity has also learned (stolen the knowledge) how to harness these substances.