Picking the wrong "normal" temperature by catching the wrong internal oscillation "wave" could result in an error of 0.22 C degrees in only a 33 year period which could be rather embarrassing. Averaging or interpolating data without allowing for the 0.22C natural oscillation of the past 33 years could result in an inaccurate estimation of current global temperature and averaging paleo climate without considering the natural internal oscillations could result in an inaccurate estimate of past climate. Errors of that magnitude would make it easy to confuse cause and effect.
Since the satellite era data is arguably the best we have, the satellite era should arguably be the default choice of baseline for comparison to past climate, whether determined by paleo reconstruction or surface instrumental readings. You really wouldn't want to catch the wrong wave would you?
Most of the organic carbon in those virgin lands was lost to erosion in the communist equivalent to the dust bowl. The ability of those lands to sink carbon was lost for decades and is only now recovering because the agricultural failure was finally admitted by the no longer communists in charge.