The line probably came from the old U.S. Army study that showed that beyond an average of three rounds, bursts fired from a M16 rifle went uncontrollably off-target (and as a result, the next M16 variant removed the full-auto firing mode altogether in order to save ammo and maintain firing discipline). Of course, this was with an assault rifle that was designed to direct its recoil backwards (minimizing the tendency of the barrel to rise with it), instead of a submachine gun that was designed to clean the room/next section of trench.
What also makes the FH2 recoil different from IRL is that in real life, you can "prepare" for the recoil by tensing your muscles, but each successive shot makes maintaining that control more difficult. In FH2, you can only correct the actual recoil, which is also only an approximation of reality. Once you find the right speed to pull back your mouse, you can keep the gun on target indefinitely, but the first few rounds will miss before you find the right speed.