NC2000 won't hit the distortion figures of the MC462. Yes, its probably a better bang for buck solution, but its simply not the gold standard.
Not understanding what you mean here as I plainly addressed that. The NC2K of course will easily hit lower distortion than the MC462 at 1100W simply because the MC462 clips long before this. So power alone can't be an argument for something being a standard unless your only problem is power. Also if you look at the various graphs available there are also points within its operational parameters/at certain impedances where both the Benchmark and Purifi outperform the MC462 in terms of distortion at lower loads, even if the averages or certain points may be in the favour of MC462 because it simply has more power to play with.
Define gold standard, and in particular, explain why measured performance that is better than human hearing is relevant. And explain why in this day and age frugal use of electricity is not important enough.
Gold as a monetary standard (where the term originates) was innately useful, fairly fungible, relatively scarce, attractive, was relatively easy to transport and trade, and held a lot of value. But it is not necessarily the most useful, the most scarce, the most attractive, the easiest to trade, or the most expensive thing out there. It is the combination of these things holistically that made it worthy of being a standard.
I would think most English speakers would say a "gold standard" is something that is regarded as being of relative excellence/high quality that has a broad and high degree of relevance, practicality, efficacy to its purpose or whatever it is trying to quantify/describe/realise. It is somewhat synonymous to the word "benchmark" (no relation to the amplifier) with more of a positive connotation or perhaps the more typical/practical connotation of the word "quintessential". If we ask for the "gold standard" of objective amplifier performance the answer may be more clear cut or more leaning on the side of perfection than if we ask for the "gold standard" of an audio amplifier in general. But at that point it is just semantics.
As a practical example, I recently had to see an ophthalmologist due to problems with high pressure in my eyes. In ocular tonometry (the diagnostic measure of eye pressure), the Goldmann method is considered the "gold standard" (no pun intended). It is the most studied method (but not the only one) it is very accurate (but not the most accurate), it is relatively easy to perform (but not the easiest), it is not the least invasive (but not the most invasive), and it can have error but it is low variance and well understood. Its use may be limited by funding, time, availability, type and severity of the patient etc. So while is clearly has its own inherent limitations, professionals have intuitively accepted it as the clinical "gold standard" when looking at the options of measuring pressure holistically, to assess if treatment is working, when comparing it to other available methods, and understanding the the objective and subjective considerations of its use.
I need to highlight that there is no such thing as gold standard in audio industry. There is no authority or governing body to set any "gold standard". Of course, you are entirely free to set your own gold standard. However, you need to note that what you set is not representative of entire world.
If you set your own "gold standard" without considering the audience or the broad nature of the topic is it no longer a "gold standard", that's just your own personal standard, isn't it? We can be further reductionist and say any opinions in this thread on what the "gold standard" is in fact a personal standard but it does not really serve to accomplish anything.
My suggestion of Purifi for example factored in performance (load-agnostic flat FR, low distortion/noise), availability, relative price, high efficiency/low heat, appreciation for good engineering/novel design to further the industry, and a power output that will probably satisfy 99% of stereo enthusiasts needs without considering any specific subjective needs like the desire to play music at deafening levels or very insensitive speakers. As most people use powered subs these days for full range (as smaller well-measuring speakers + sub generally better FR performance than most full range setups at cheaper prices), the necessity for massive amounts of stereo amplification are at an all-time low.
There may not be any universal or governing body for audio enthusiasts but we can still understand the scientific and practical purpose of what an amplifier is for and what makes a good one or bad one, use established best-practice conventions in engineering, use knowledge of psychoacoustics to understand how much and what types of distortions or response/impulse characteristics are audible, we can still use calculations and general population preferences to determine how much power is necessary or ideal, we can still compare and contrast to other available products and what features may or may not be available or how much they cost, and what you get for the price. We can even weigh how important having more inputs or cosmetic features are into buying decisions.
Like the Goldmann test I described above, no amplifier is going to necessarily be perfect or ideal. But it's very possible to objectively analyse choices and considerations that have a subjective nature and make contextually objective conclusions and compromises when it comes to products that are designed for broad groups of people. It is entirely possible to accept a realistic "gold" standard that's grounded common sense and the nature of the industry even if your own personal standard does not align with it (preference curve studies are a good example of this).