Because it can come more than 2 minutes earlier
When I like to play outisde the meta (I play 1v1), I go only for medic truck and use a JP4 to deal with tanks from the second row, supported by 1-2 Raks and some Volks with Schrecks. Luftwaffe gives you elite infantry, and also HMG34 to protect flanks. Don't forget mines! If I'm feeling really lucky, I even get an ISG to shoot enemy weapon teams / blobs
In case the game drags out longer, you can still go for Flak truck and a Panther or even Obers if Falls are not enough for you. But with their PzFaust, Falls synergize well with the JP4 IMO.
vs US makes sense but vs Soviet Heavy's i find it hard to make good use of it, fails to pen IS2 even with HEAT rounds.. its kind of good in maps with choke points though but still i dont get it vs Soveits that 8 min Flak truck is too crucial for me and so is 9 min obers.. i can deal with Early T34s with soem raketns and mines and couple of shrecks.. Obers will mow the rest..