You rather answered your own question...
Back in the day, the most demanding application, with respect to the regulation of 12V (or lack thereof), was probably the vacuum tubes made to deal with it. Automotive regulators were poor (mechanical), so automotive radios used tubes with heaters specified for 12.6V nominal operation which would have adequate emission (and freedom from cathode poisoning) down to, whatever, 11V or so, and adequate lifetime (and freedom from diffusion and whatever) up at 14 or 15V. There were also tubes meant for direct operation at 12V (plate supply), awful specs but, for what they were used in, better than a stupid vibrator supply!
And the history goes back a bit further than that, still, with 6.3V being more common in autos (sometimes positive ground, at that), and 2V and 6.3V being common A battery ratings (again, yep, tied to lead acid), going back to the beginnings of radio itself.
And what do you really need regulated 12V for, anyway? A lot of regulated supplies are really just arbitrary, and the circuit either can do just fine on variable power, or can be made to behave (e.g., an amplifier using op-amps, instead of discrete transistor circuits with shit PSRR).
Anyway, if you must have a DC-DC converter, there's SEPIC, Zeta or buck-boost ("flying inductor") for that. You'll probably want something like that anyway for a much wider input range, accounting for dips (down to 6V during cranking, say) and swells (15V max charging, but also >30V in the rare load dump condition). Nothing at all wrong with doing that, pretty standard. If you require efficiency, then a DC-DC at all is required; and if you can't choose a lower supply (like 5 to 10V) to use a buck, then just change topology, probably choose a different controller, and get on with it.
Mind, also, 12V is completely arbitrary, outside of the nominal lead acid 6S discharge voltage. 14V might be a better tradition nowadays, with lithium batteries being dominant. Or you could use 11V, or 10V, or anything else just as well. MOSFETs are typically spec'd for Vgs(on) = 10V, though 12V is commonly used to supply drivers. Anything from Vgs(on), up to Vgs(max), could just as well be used. Why is 12V used, indeed?
Tim