Because an FJ company can totally afford to throw away its high pool cost infantry like that....
If you need to replace your FJ that fast on the field, you are already losing.
You keep discussing large pool costs when the fact is that FJ's don't take up as much as you think they do. Like I said, I run 10 falls with 8 other inf squads at -14 for the Inf pool. The inf pool for luft is at 84, which is HUGE. Mysthalin's reasoning is a very solid reason to run Luft alone. They are easily the most versatile form of elite inf that EIRR has to offer, coming with the largest amount of possible upgrades making them useful for any situation except for heavy armour, in which they can still faust and use slow mines.
FJ's provide more of a scare than Paradropping AB does, due to the fact that you don't know what upgrades they have on them. When you see AB drop you can instantly tell them apart from AB Rifles, so you can counter before they hit the floor. 2x FJ's with fausts and fg42's (Or Boys) are good enough to scare off most forms of light armour and inf. The only cost-efficient hard counter would be m10 or crom crush.. Which happens more often than I think anyone would like to admit! This versatility alone makes Luft a powerful doctrine.
In regards to combat behind enemy lines, any decent player wouldn't have trouble eliminating any form of inf, regardless of if it's AB or Falls!
