That's very true of petrol driven engines with 'normal' a/c compressors but when considering electrically driven compressors, as fitted to hybrids and EVs, running the a/c will have a significant effect on battery range.
That said I personally wouldn't turn off the a/c simply because I value the comfort afforded by a well control cabin environment more than range. Also keeping the a/c running will ensure the seals remain well lubricated and intact.