True. The record companies missed out on making a 12" disc when they cooked up high-res formats. Like a Laserdisc for sound. Note, however, part of the point [at the time] was coming up with a format that would be SOTA [or at least make claim] but also be playable in the car. Not that I've ever seen an in car SACD player.
I suppose that would make it a good "merch" format today.
SACD very much feels like a product of "pre-Internet" thinking. I imagine the idea, particularly with "hybrid" SACDs that had a "CD" layer, was for the world to transition over a period of time to SACD, with the marginal costs of adding SACD capability to mass-market consumer products being negligible... but royalties due to Sony/Philips would be non-negligible, and the record companies could have a bonanza through the sale of repackaged content, as they did with CD. I suppose, too, the manufacture of "hybrid" discs may have posed difficulities for the duplication facilities of pirates.
Pretty much around the time SACD had really launched, though, I already had a 2Mbit/s cable modem connection at home, and the release of the Windows version of iTunes was around the corner...
As for in-car SACD players, never heard of such a beast... but Google has.
https://www.stereophile.com/content/sacd-dvd-audio-dvd-car-two-sony-players-1