Weight, per Ram. It's a pretty simple job to have the winch and intercooler.
Aftermarket example:
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I seem to recall when the PW first made its reappearance with the winch, there was no Cummins option based SOLELY on the intercooler issue. As in, because of where the winch mounts (directly between the frame rails behind the bumper, not lower and further forward like every aftermarket bumper out there), the intercooler can't be placed in its normal position (directly between the frame rails behind the bumper). On my '22 CTD, there would be no way to have a FACTORY mounted winch without relocating the intercooler, because it mounts EXACTLY where the winch mounts on a PW (I had a '17 PW previously).
So no, I don't think it has to do with weight. I mean Ford has Tremors with PSD's and the winch available, but their intercooler mounts differently. The weight is about the same as a CTD.
I'm pretty sure it's got to do with real estate behind the factory bumper. Sure, if you put an aftermarket bumper on that moves the winch forward, you absolutely could have the winch in front of the intercooler. But they can't physically inhabit the same location.