"The room can totally wreck, or make, a system"

I sang this song here for many years. :)

The sound quality result not from the room or the systems but from the relation between specifics ears/brain, specifics system parts and speakers, specifics room (including the material acoustic content of the room and his geometry,size and topology). it result from vibrations controls and from Electrical noise floor control...

The rest is useless upgrade when we reach an optimal purchase point for our budget.

The worst part about a bad room is how it will constantly send an audiophile into a consumer merry-go-round.  Constantly trying to improve the sound with better speakers/cables/etc.

Too bad all speakers aren't as easy as Ohm. You tell them the room volume and they give you the appropriate speaker.

I'd rather start with room friendly speakers. From what I hear, 1st order like Thiel are the worst. Even my B & W with steep x-over got bad room reflections when volume was turned up. Sound became confused and muddled.

As you all of stated, room treatment is critical. Probably the most important part of your system. You can do more harm than good however, if you don't know what you are doing, or just put some things in the room, thinking it will make an improvement. I had treated my room in a manner that I thought made sense, treating obvious reflection points, etc. However, the cheap products I used were far too thin to trap anything but high frequency and I didn't have near enough bass absorption. I also had too much absorption and not enough diffusion in spots. 

I re-did things with professional advice from GIK and their free consulting/room design service. It is an excellent service and free of charge, but of course they hope you will end up using their products. I did, and the results were 100% better. GIK is excellent and there are many other great products on the market. Spend the money and do it the RIGHT way. 

You can do more harm than good however, if you don’t know what you are doing, or just put some things in the room, thinking it will make an improvement.

More harm than good...depends. Some rooms are really bad to begin with, and almost anything (properly placed) will help. But generally I agree.

And learning REW -- https://www.roomeqwizard.com/ --and buying one $100 Umik gets you on the way.

Read about REW. Watch a couple videos. Learn what you’re trying to address first. Then buy conservatively what you probably need (look locally first) and then add incrementally, measuring all the while. This is how you establish a correlation between what you hear and what the measurements show. Repeat as needed.