Why bookshelf type speakers are high end

This is another MUST READ.

I love seeing bookshelf speakers costing tens of thousands of bucks that are truly high end

Magico has done very expensive bookshelf speakers. There are many other examples.

Bookshelves obviously cannot reach down to 20hz., but down to 40hz their sound is balanced.  This is true high end territory.

Many audiophiles do NOT use their standmount speakers with a subwoofer. Despite this, they are enjoying high end sound.

LS50 is an example of a speaker that has achieved rave reviews. I have heard them and can confirm they are excellent.

Do not be fooled by naysayers . If you want high end sound, you don’t need perfect bass down to 20hz.

Most towers don’t have the necessary extension to reach anywhere near 20hz, and it’s better to offload the bass load to a subwoofer either way to reduce the load on your amplifier/receiver.

There's also not that much musical content below 40hz for most music genres anyway, so extension down to 20hz (which requires massive sensitivity trade-offs) isn't really worth it, and for home theater use it's already well established that it's better offloaded to the subwoofer's amp which is impedence matched for the 
Only earbuds are high end.

All my men wear earbuds or they wear nothing at all.

There’s also not that much musical content below 40hz for most music genres anyway, so extension down to 20hz (which requires massive sensitivity trade-offs) isn’t really worth it

You might think theres not much musical content below 40hz if youve never had a system that can do 20hz window rattling bass, which i have had in case you are wondering.

If it cant reach its not high end. If you dont care about high end, and want to use excuses like "theres not much content below 40hz", to compromise, youre not a real audiophile. It damages the reputation of true audiophiles when you say things like that.

I just found out that my cell phone speaker goes down to 20hz. Does that mean I am a "true audiophile"? I would be crushed if my audiophile reputation was compromised.
The bull elephants are pleased to know your phone is in estrous. Prepare for it to be crushed. : )
Is that insufferable troll slithering about again ? Must Ignore, is the best advice I’ve seen in this forum.
@kanji I too have a system that goes below 40hz, manufacture says 
  • Frequency response. 21 – 25.000 Hz -3dB.
However, I have and had several bookshelf speakers.  These smaller speakers have their place in the market.  Probably the #1 reason is space, but sometimes people prefer a smaller profile and clean look.  

These speaker, typically 2 drivers, I find have great imaging and easier to integrate into a room.  Plus in a smaller space just sound better.

Your absolutes are crazy.  Nothing in life that I know of is all encompassing.  Is a Porsche able to navigate the Rubicon trail and it not a luxury, or carphile vehicle?  Is there a food that satisfies every taste on every occasion and that food not considered the best in its category?

please let me know some absolutes outside the audio industry.  I am curious on what you have found.
I prefer the way stand-mount speaker image and the other factor is that it is very common for the optimal spot in a room for bass reproduction to be different than the optimal spot for midrange and treble reproduction.  

I produce a series of stand-mount speakers (soon 5 speaker between $2K and $7K) partially for this reason.  I will also do a floor-stander as this is where the bulk of the market is but I will likely always keep stand-mounts in my home with subwoofer(s) as that is my preferred sound.  
I have two sets of stand mount/ monitor speakers in my second and third systems.
Both have their very good strengths in imaging and top end detail, both suffer a little on low end extension (obviously, only so much you can do with a 5 inch driver and small box!).
But are they dynamic, cohesive and engaging?
Heck yes.
High end?
Nope, who cares.
If you take a full range speaker that goes to 20hz and then do a high pass filter at 50hz, thats what a typical bookshelf speaker would sound like. A subwoofer is typically added without any high pass filter on the standmount and even if there is, its usually quite low whereas in a 3way floorstander the crossover point could be as high as 200hz. 
I've heard several speaker systems that cost well in excess of $500k, and not surprisingly, none of them came close to perfect.  Really good sound?  YES, but, there is no such thing as a system without compromises.  Compromises are inherent, even if there are no cost or space or room acoustic limitations.  You optimize one thing you have to compromise something else.  I would never deem any one choice of trade-off as being wrong.  Several of these mega-buck systems had ultra-expensive, multiple 18" woofers, but did not come close to delivering 20 Hz (except way down in amplitude) because the bass was being optimize for speed, tone and other qualities that mean restricting the fore and aft movement of the cone.  

My own system has twin 12" woofers per channel that also don't really do 30 Hz, never mind 20 Hz, because they behave WAY better with hardly any fore and aft movement.