Nearly all manufacturers do not advertise/exhibit their product measurements? Why?

I have plenty of this data.  It falls in these categories:

1. Company never bothered to make any measurements.  You can count on this being the reason in just about any audio tweaks (cables, etc.).  I know this because they are often surprised by my measurements.  But when I ask them for theirs, they have none.

2. They make very rudimentary measurements often using obsolete audio analyzers that don't remotely present the deep dive that I provide in ASR reviews.  One of the main reasons for this is the cost of instrumentation.  A proper audio analyzer sets you back US $30,000.  A proper speaker measurement requires spending $2K to get measurements in anechoic chamber or buying $100,000 Klippel NFS that I have.

3. They have the right measurements but don't want to publish them.  Harman as noted falls in this category with their speakers.  Their marketing department thinks it will be "confusing" to people if they publish detailed measurements.  Engineers and product planners disagree and leak it in forums and such.  So the information is there but not in product pages.  

Note that #3 is quite rare.

Note that even if you had measurements on cables for example, they would be useless.  I don't know about you but I don't listen to cables.  Or power conditioners.  Or AC cables.  I listen to the output of my audio system.   You would think if these things change the output of your system, these companies would be anxious to show them in measurements.  Or failing that, using controlled listening tests.  You get neither.

Instead, companies talk about such things as "lower noise," "EMI," "Jitter," yet no measurements are shown.  Instead, some theories are put forward that sound good to consumers.  Sadly some audiophiles buy into these unproven claims so companies think "life is good so why bother."

The industry is transforming though because if they don't measure, then I might.  :)  Smart company would want to get ahead of the game and make their own measurements.  And offer them.  Schiit for example when through this major change from using obsolete measurement gear to what I have now.  Reports are now released with every new product.  

Audiophiles have gotten quite a bit more educated and are driving this change.  I routinely hear from companies saying people want me to measure their gear before they buy them.

I hope every audiophile is supportive of more information than less and will push the industry to provide comparable and reliable information about their products.

I should add that as soon as Schiit started to measure their products, their performance shot up through the roof.  It created a new market for them with that improved performance.  So there is business opportunity there for companies.

1) It is a good thing that measurements can inspire companies to bring the performance up to a higher level. Consumers should be taken seriously.

2) We listen to sound that is generated by components who work on rectified, filtered, stabilized, modulated, transformed electricity. Everything between the grid matters. That includes all cables and connectors, just as capacitors or diodes for example.

3) Cable companies should not make false claims and deliver proof. I can agree on that part. It can be hard to listen for those tiny changes. Recently I discovered that a cheap Van Damme tourgrade starquad bested my Siltech. I am a pragmatic audiophile so I sold it on eBay. 

4) On the other hand, people should not make claims about the hearing capabilities of other people. If multiple people subjectively can describe parameters of a component that can’t be supported by measurements (yet) it should be taken as a starting point for further investigation. We don’t all have 1000+ people at hand to conduct (DBX) tests for any statistic significance. Or have expensive test equipment. Interpret measurements correct and be humble about your personal bias as a tester or audiophile. I can live with that.

@tantejuut 

4) On the other hand, people should not make claims about the hearing capabilities of other people. If multiple people subjectively can describe parameters of a component that can’t be supported by measurements (yet) it should be taken as a starting point for further investigation. 

Yes, further investigation would be for said people to conduct a blind test to make sure that only their ears told them that.  If other senses were involved, naturally measurements would not show it because we are only measuring sound.

With respect to many audio tweaks like cables, the above test is dead simple as levels don't change.  So all you have to do is hide the identity of what is being changed and see if the listener can detect the change at least 8 out of 10 times.  You can take seconds or days to listen for such a change.  And do so in your own relaxing home environment, system and music.

If you don't want to do that, then the road ends there really.  No sense in then insisting that you are "hearing" a difference.  Enjoy your system and music but don't engage in trying to convince others that you are right.  You will lose that argument in any evidence based discussion.