They booked a studio for the remix that lacked enough board inputs for all the channels and reverbs. This shows up in many early Columbia or Epic quads as reverbless instruments (a glaring example is the dry, hokey synth in Great Suburban Showdown on Streetlife Serenade).
The lack of reverb on most CBS quads probably has something to with SQ compatibility as well. Some of the later CBS titles that more closely resemble their stereo counterparts tend to decode worse than the earlier dry 'four-corner' mixes. The O'Jays' Family Reunion would be a good example - it's an incredible quad mix with practically every nuance of the original replicated, but the SQ LP is a mess.