I hope we don't come over as critical, when the intention is to kind of, explain that the 50's recording techniques matched the genre of the music. Like in the early 70's when ordinary studios were recording 'stereo' and getting excited because they missed the point, and were recording two channels - a left one and a right one, and deciding which things were on the left, OR the right, and the few that would be on both. Anyone, me included, at that time assumed this was the correct thing, while the Germans and the BBC pushed hard for realism and that feeling of being there. Gradually the hard panning got done much better - but this 50s 'sound' or 'technique' was just the day to day recording technique for the singers and musicians. You've taken your understanding of modern recording and produce a sort of conclusion of the 50's version, but sort of missed the important bit. Everyone had bands/small ensembles - small ones to big ones, so if you had one recording track or 4 (wow) the object was to record what was going on and balance it for either transmission or recording in1 or 2 track format. The overdubbing, bouncing, even sound on sound were late 60's and early 70's techniques. In your video you mentioned Les Paul, who with Mary Ford DID start the multitrack and layering techniques in 1949! He was so ahead of the times really, and was attaching extra heads to the Apex machines he got hold of. everyone talks about 'How High the Moon' - recorded in 51, with a single ribbon mic for her voice, everything else DI'd, using modern terminology. So he had tracks recording, being delayed, added back in, voices doubled and repeated amazing stuff, but he was pioneer. I often wonder if Les Paul guitars would have looked like they do if he had not needed a big space for tape remotes!
The thing to remember though is that this kind of recording was NOT normal. We think of the 80s as the era of the synths and synth bands, but in 73 Goodbye Yellow Brick Road had a huge synth part starting an album - and without multi-track it couldn't have happened, but synths were available before that time - they existed in the late 60's - as in Wendy Carlos's Switched on Bach. I never touched a synth until 1976 - none in the music shop and no friends had one. By 1979, I'd got my own.
If you listen to popular music from each decade, there is a sound. 40's did sound kind of war time somehow, 50s would be mum and dad easy listening music with a few RnR starting to creep in, then the 60s with the beat bands, then modern pop in the 70s - the sound created by the music. I've been listening to some music from the 30s, and it sounded really clean and clear and then I discovered it was recorded recently, by a small dance orchestra playing with a singer in a ballroom. It sounded authentic period, it wasn't at all, it just captured the band playing the right music in the right style.
God - this turned into a history lesson - sorry about that - but I think it really is important. Lots of folk buy a Shure 55 mic and assume they will sound like the 50s, because of the mic - they don't!