Wouldn't life be nice if there was one official "master" that could be compared back to in order to objectively measure "what is true hi-fidelity". The reality is the mastering engineers do NOT stay true to the original master tape especially on older recordings where the mastering engineer know he was mastering for vinyl and so made changes that differ from what the first digital transfer engineer did and then later "re-masters" had to be different to justify their existence so yet more changes were made and on and on over the years. With all these changes over the years it is possible that the original vinyl is "closer" to the master tape but in many cases we will never know as the original master tapes are lost, ruined, or burned up. I find it interesting to listen to different versions of my favorite recordings including the "original vinyl" even if I prefer later digital copies and remasters.
I was listening last night to a vinyl version of one of my favorite 90's CDs (Everything But The Girl, Amplified Heart). The mastering was at Abbey Road, 1/2 speed mastering. I still prefer the digital version. Not just due to familiarity, but it sounds overall better and cleaner and more relaxed in the high frequencies.
On the other hand, to your point, I have a large collection of Library Music LPs. Library, or "production music," was created on spec and sold to companies for use in films, tv, commercials etc. They were excellent recordings and a small number of records would be cut from the original tapes and sent out for productions to sample the tracks. Then select cuts would be ordered on tape copies.
For a long time the original (and very rare) LPs were the only way to listen to this music. And many sounded absolutely fabulous - big, rich, clear - ticking all the 'sound quality' boxes. They had some fantastic engineers doing some of this stuff.
At one point these tracks started to find their way on to digital releases, collections etc. I bought (or streamed) some of those and often the sound quality didn't at all compare to the record. It had all the earmarks of a lower quality source (maybe many generations later?) being used for the digital versions (or someone doing a bad mastering job, making for dull, thin, undynamic sound). I would place my bets the vinyl versions were better representations of the sound quality of the original tapes.
And in fact that seemed to be born out: later, some of the companies that owned those original tapes (e.g. KPM) started transferring to high quality digital.
Those digital releases sounded superb! MUCH more like the sound quality I'd been enjoying from the LPs.