As long as the open loop gain is sufficiently high, the "accuracy" of the op amps transfer function is not a factor. The transfer function is determined by the feedback loop, not the op amps open loop transfer function.i agree it appears to work on a general scale...but how about the transfer function of the opamp...is it accurate when operated like this...and if not, then that means the feedback loop calculation for the smps has gone awry....bad news.......
The open loop gain of that op amp does drop when the common-mode voltage is zero (as per the data sheet) but it still is more than high enough to have no significant effect on the closed loop response.... good news...