You're extrapolating wildly from a few anecdotal examples.
More than a few, sadly. I spent a lot of time with some hardcore guys who worked for Sound Investments in Glendale WI, in the 80s. Yes, once you get past 97%, then it's rarely better, only different, and I am well aware of component matching.
The folks at the store did me a big favor and hooked me up with local mechanical genius Gene Zanow. I handed him my Thorens TD125 Mk II. It had a Decca unipivot arm. He was to give the arm minor upgrades and tune the table.
What did I get back? The platter was trued. Bearing polished. Springs adjusted so it would move up and down. That tonearm? Gone. Arm board, gone. Wiring, gone. Original arm lifter, gone. What did I receive? A custom-made tonearm that Gene made himself. It was an "Optimum pivot" desgin. The pivot was on the same plane as the record. He made me two weights, one for the average cartridge and one for my beloved Decca Mk IV.
He did keep my AudioQuest sorbothane mat!
I've mentioned some of my favorite components. Mark Dineen's B100 preamp by ADC... one of the most neutral preamps ever. QED 440 bridged solid-state class A amplifier, amazing. The speakers, I can't describe them because boutique. Nobis Dm-3t made in Milwaukee. They were designed to be ESL-63 killers. They pretty much are!
That store made and sold a lot of interconnect custom made. Star-quad microphone cable. It worked pretty well.
My point is that I leared everything you've mentioned decades ago, and did things about it. Honestly, I got out of it because I got tired of screwing around with other people's mistakes (don't get me started on Counterpoint) and I get good equipment and service from Parasound. I sometimes think I want a Halo integrated amp. Maybe some day.
So, please. I know. No need to explain.
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