High End System Building. How important is the matching, cabling and room? Thoughts ?

I think the bullhorns and brashness come from folks tired of trying to find ways to instill the broad concept of how the word “test” can be (and oft is) misused when discussing  anecdotal (personal) sampling that doesn’t conform to any measures established in ethology or experimental design - measures that’ve been defined for decades.

”Belief” that certain expensive cables or unquantifiable system synergy can solve concepts of acoustical shortcomings in an infinitely variable music playback system should be no offense to anyone, as long as they’re not phrased in any way to suggest true research (properly replicated, free of bias, any other analytical assumptions met, repeatable). Indeed, belief is an unquantified faith in something that is not proven. 
When the tone takes on one of factual evidence, folks who understand evidence in a scientific and/or legal sense might go object. It should be expected.

If some folks spend a bunch of their money for having it, but can’t be bothered to educate themselves on how the engineering of devices (e.g. audio cables) should not exclude rigorous experimental design-based testing to meaningfully support their worthiness, I for one cannot be bothered to care.

If a used care dealer dupes a single mom to pass off a hoopty for trying to get to work each day, 6-7 days a week, it should be a legal matter. If someone buys 4-5 figures’ worth of cables because they didn’t take (or pay attention in) a high school or uni science class and have enough spare time to concern themselves with invisible nuances in the music replay-iverse, not my concern. Except that sometimes it’s been fun to sit quietly and watch!

Just sayin’ 😉

benanders

I think the bullhorns and brashness come from folks tired of trying to find ways to instill the broad concept of how the word “test” can be (and oft is) misused when discussing  anecdotal (personal) sampling that doesn’t conform to any measures established ...

The "bullhorns and brashness" you mention seem to come mostly from measurementalists who dismiss with insult or a wave of the hand any empirical evidence that causes them the slightest discomfort. If they are "tired" of that evidence, perhaps this isn't the place for them.

long story short, rooms matter alot, often at least as much as the cumulative effect of all the equipment

but if you have a bad room, a lot can be done to make the listening experience fairly good, most notably minimizing room effects by going nearfield or semi nearfield

room treatments can help in some difficult rooms, but often a very bad/weird room just cannot be handled just by treatments

long story short, rooms matter alot, often at least as much as the cumulative effect of all the equipment

Exactly and it is my experience ...

but if you have a bad room, a lot can be done to make the listening experience fairly good, most notably minimizing room effects by going nearfield or semi nearfield

You are right for the "minimizing part...But even nearfield listening as you implicitly suggested   ask for some acoustic treatment of the room to be optimized ...If you want a soundstage over the speakers in depth and encompassing the listener near field position for sure even in near listening you must put some reflective waves to good use .....

room treatments can help in some difficult rooms, but often a very bad/weird room just cannot be handled just by treatments

This is why in my "difficult" past room i used not only passive treatment with materials to reach a good ratio between dispersion , reflective areas and absorbing area and their location , but it was not enough ... I used ACTIVE mechanically tuned devices called Helmholtz resonators in a grid fashion all around the room to change the zone pressure distributions to my liking ...It was not esthetical , you needed a dedicated room but it cost me nothing , it was fun to experiment and the results were stunning ...A soundscape encompassing my listenin position at peanuts costs ...

I’m going to get straight to the point. A lot of us are plug in play. We can’t do anything to the room depending on your living and family situations. If you want to spend less you can. You can improve your room using a number og @mahgister suggestions as well as many others. But at the end of the day. I been doing this a long time now. I want to get my hands of the best equipment I can afford. Some people spend on luxury cars. I like Audio and I’m going to use what I learned to seek out the best equipment, synergy and cabling possible. I will build my system on those foundations. I can’t do anything to my room. All I’m saying is that you can get great sound out of a bad room. You just got to pick the right things to get you there. My system will sound good almost anywhere you would probably put it. Do what makes you happy. If you don’t like spending on high end stuff then don’t. But based on what I’m experiences in my home environment I’m extremely happy with my set up. I will keep doing me. There is nothing like well designed gear that eliminates noise and distortions and is still musical. My journey has placed me at the point I’m at and I’m happy. I’m listening to some beautiful Ahmad Jamal as we speak.  The piano sounds amazing!