The f/1.5 is an actual rating. It's the ratio between the focal length and the diameter of the pupil. It's important for shutter speeds, and relative performance in low light (before all the computational duckery). I can compare roughly a phone camera that's at f/1.5 vs a phone camera that's at f/2. Making a low f/number lens is more difficult than a high f/number lens, regardless of actual focal length.
And I've got a non-35mm mirrorless camera. All the lens I've got are marked with the true focal length and true f/number, not some "equivalent". My iPhone camera photos' metadata show the focal length, both true and "35mm equivalent".
You're not disagreeing with my actual argument, which is just "they should use the equivalent ratings for both focal length and f-stop". If you prefer physically-based specs, you should be demanding that they also say the focal length is 7mm or whatever.
> It's important for shutter speeds, and relative performance in low light
It's completely useless for determining low-light perf without knowing the crop factor.
> I can compare roughly a phone camera that's at f/1.5 vs a phone camera that's at f/2
Not without knowing the crop factor. You're falling for the marketing.
And I've got a non-35mm mirrorless camera. All the lens I've got are marked with the true focal length and true f/number, not some "equivalent". My iPhone camera photos' metadata show the focal length, both true and "35mm equivalent".