"Rubber Soul"

Can any of you answer the question of, Why was Rubber Soul and some other Beatles lps, recorded/mixed with no center channel?
I'm listening to my Capitol & Japanese pressings, and started wondering about this again.
Hard left and right pans were the style back in those daze. Plus, the early Beatles albums were recorded on 4-track machines and use multiple overdubs to achieve what is currently done with multi-mics and a 24-track recorder.

Buy the mono box set!
The Beatles recorded in mono up to and including the so-called White Album. The stereo mixes, largely an afterthought, especially on the earlier albums, made use of the left and right channels -- the new thing -- as a toy.
"Hey, look -- we can put the vocals over here and the guitar over there! Isn't that cool?"
The Beatles were not alone in using this technique, but many of the other bands that did it have been largely forgotten -- or are at least not too frequently listened to.
I've got both the stereo and mono boxes from a few years back and listen to the monos much more often. If you love The Beatles but find the odd stereo mixes a distraction, I'd highly recommend the mono box. Fabulous songs without the gimmicks.