ifr in an airplane is a lot easier than ifr in a helicopter. Airplanes are inherently stable. Helicopters are very much not!
next time you’re in the goo with a bit of unstable air try reaching over and shutting “George” off and see exactly how difficult it is to maintain heading and altitude.
Helicopters are not certified to fly IFR without an autopilot or at a bare minimum a second qualified and current pilot.
lots of airplanes are IFR certified single pilot without an autopilot.