What are we objectivists missing?

Perhaps we’re coming from different perspectives. To me subjective and objective could be described thus;

Subjective observation is centered on a person’s own mind and perspectives, as opposed to being general, universal, or scientific. In this way, describing an observation as subjective often implies that it comes with (or is based on) personal biases.

Objective;

Objective most commonly means not influenced by an individual’s personal viewpoint—unbiased (or at least attempting to be unbiased). It’s often used to describe things like observations, decisions, or reports that are based on an unbiased analysis.

Let’s say you’re a restaurant critic. There may be certain foods that you subjectively dislike—ones that are just not to your taste. But when critiquing dishes, you must leave your subjective tastes aside and be objective about what you eat—making objective judgments about things like how it’s cooked and seasoned and how the ingredients work together. Even if you’re served a dish that you subjectively don’t like, it’s your job to objectively assess its quality.

In a scientific experiment, your hypothesis might be based—at least in part—on your subjective opinion about what the results will be. But science is about being completely objective by gathering data and making conclusions based on the data.

In everyday life, your objective opinion is the one that sets aside your subjective preferences or feelings about something and instead assesses it based on facts and reality.

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Personally I dislike tube amps, inefficient, to much trouble to maintain, but there are tube amps that are well made, do a competent job within their specs and if someone likes them it’s none of my business. I've heard tube amp I couldn't tell from Solid state it's just my personal bias. Different strokes for different folks. If they start claiming they are superior to Solid State and sound better then I need more than their subjective opinion. How are they superior and have you compared tube amps to solid state in a blind listening test and pick tube amps better than chance.

Henry Ford and Charles Lindbergh admired Hitler.  

I'm totally for people sharing their subjective preferences. I take them seriously and accept that they really do prefer the equipment they say they do under the conditions they are using it. If they don't care about how measurements might correlate to sound preferences that's perfectly ok. No need to do blind testing if you're not interested. 

To answer the OP post, all evidence suggests that under properly controlled conditions we do know how to measure audio signals in a way that accounts for the limits of human hearing. In uncontrolled, sighted settings there are a huge number of variables that change our overall perception of sound quality. Nevertheless, between any two models of speakers  it's easy to measure differences that fall within the known abilities of human hearing, often even between two speakers of the same make. There can be all kinds of interesting interactions between different components, such as amps and speakers, or even pre-amps and amps, and dacs and pre-amps, and even the cables used to connect them. This need not be the case, but it might be preferred to introduce audible non linear responses between these devices to give people room to tailor their sound by mixing and matching components. I believe that almost any speaker in any room can benefit from a little EQ - unless someone just hit the jackpot with the perfect match of room and speaker. Sometimes a little noise and distortion of the right kind can be nice too.