actually, the mhz is an actual fact.
Yes, and so is the fact that the Pentium 4 has a 20 stage integer pipeline. Would it then be OK for Intel to advertise the Pentium 4 as having a 20 stage integer pipeline which is supposedly "better" than the Athlon's 10 stage integer pipeline? Do you get the point? Just because it's a fact that the best P4 has a certain MHz (e.g. 2.53GHz) doesn't mean it should be used as a measurement of performance.
Similarly, it's not precisely clear to me how AMD comes up with the model rating system, it's based on some formula supposedly. But even if AMD just came up with these numbers from the top of their head, they're still an accurate measurement of performance when compared to the targeted P4 CPU (2000+ versus 2GHz for example). In general, when you look at a wide array of benchmarks, this is true (funnily enough, I've meet people that wouldn't admit a 2000+ is generally faster than a 2GHz P4...).
Yes, I know AMD says its ratings are derived from the previous generation Tbird, however it's quite clear it's versus the P4. It's confusing in some ways that AMD's official statement is that the model rating system is a comparison to previous Tbird generations (however it's possible that AMD just didn't want to admit that Intel is the standard to compare against).
However, knowing that the model rating system equates very well to the P4 (and conservatively in most cases depending on the processor) it's better than only advertising the Athlon's MHz, which would be even more misleading because MHz does not = performance, even though the MHz measurement is a fact.
Is it just zealotry to accept the model rating system for what it is like you claim Sid03? Well I don't know, would it be just zealotry to have a scenario where a common, everyday Joe Average walks into a store and picks up a 1.8GHz P4 system instead of a 1.73GHz AXP system thinking the P4 system was the better performer all because people like you claim that "MHz is fact, even though it doesn't accurately measure performance"? You tell me Sid...