IIRC, the Beatles “Sgt. Pepper” album was among the first stereo-mixed albums released. As much fame as that particular album has, the original mix is really bad. Drums all left, guitars all right, nothing in the center. It sounds weird to modern ears!

Also IIRC, I believe George Harrison’s kid remixed it properly, just a handful of years ago.

One of the reasons being that more people had mono systems so the stereo mixdown was just kind of a "for fun" afterthought. They didn't take it as seriously.

Even worse is when they keep screwing with the panning. I can't stand Led Zeppelin II for that reason. Someone just couldn't stop messing with the damn slider, right in the middle of songs. The ones with merely bad, but static, panning are far more tolerable.

Because the analog equipment back then could only do binary panning.

I've heard this is a recommended paradigm for mixing, to only ever pan things R, C, L and nothing in between, but it doesn't make sense to me. Possible because i have to mix on headphones, but it sounds much too extreme to me. Sure, _some things_ can go all the way but i generally enjoy to fill the space between the far edges, and allow some reverb busses to blur the lines a bit if needed.

Is hard panning really strongly recommended like that, or just a hold over that the old heads learned and passed down

No, that's complete nonsense.

That’s totally not true. The original stereo patent from the 1930s is based on M+S signals, not separate channels, and was born out of a desire to position sound across a stage (movies).

By the time the hard-panned records of the 60s were made the technology was already old, it was just a stylistic choice.

I don't think we stopped doing it because it's gimmicky.

Recordings in the 1960s were mixed to be played back on stereo speakers. You can hard pan stuff and in your living room where you listen to it, it will produce a nice pleasant stereo image because each ear can hear some of both speakers.

Today, audio engineers mix music to be listened to primarily on headphones. If you pan something hard left, it's literally not going to be heard in the right ear at all which sounds horrifically artificial.

So now music has to be mixed to synthetize a pleasant soundstage when heard on headphones.