Umm...
You can get one in .30-06 or even .35 Whelen starting this year. I realize that neither of those are long range 'uber' thumpers like a .300 Ultra mag, or a 7mm mag, but as far as reasonable application of force on any game in North America...thee is no real difference.
Now...if you were lamenting the lack of 'dangerous game' calibers, then I probaby agree with Dionysusigma: Even if NEF made a .375 H&H, a single-shot wouldn't be my first choice to take in to the brush looking for wounded game, guide or no guide.
greg