All speakers have a little EQ built in

And those calculations/crossover designs are for the speaker when in a large padded cell.

'In the Beginning', speakers came with Level Controls, so they could be adjusted for your listening space, your preferences, your particular hearing including 'typical' age related, progressively reduced ability to hear highs.

'In the Beginning' Preamps/Receivers came with important features i.e. Stereo/Mono/l+r to r; l+r to l; phase; balance; low and high filters, tone controls. These days those controls can be 'in' or 'out', no reason not to have their potential benefit(s)

Sadly, those speaker level adjustments were often unreliable over time and the cause of much frustration.

Modern speakers are not designed for an anechoic chamber, but the measurements may be done that way in order to properly set crossover points and alignment. No competent speaker designer I know of would build a speaker for an anechoic chamber.

I do however agree that good tone controls in your preamp are wonderful. I’ve had gear with good and bad tone controls, so I can understand the reluctance of some listeners to use them again, but good ones exist!

No one's room and no recording or hearing is perfect.  Let's be good to our enjoyment of music and use tone controls!

Yes for sure. 
 

I tend to think drivers that need a lot of smoothing through crossover parts get robbed of some of their sensitivity which results in heat build up and loss of dynamics. Good drivers are super important, far more important than fancy box materials and crossover parts (all things matter though). 
 

As for target curves I am on board with Harman’s studies of about 5db in room slope from 200khz-20khz. That seems to work well in my room. Oddly I think Harman’s headphone curve is crap and far too bass heavy.  

@erik_squires I appreciate your enthusiasm for tone controls.  Early in my journey I appreciated the option to by-pass tone controls; why, I appreciate simplicity.

And in this journey personal preference makes a difference and its wonderful there are so many options.

@overthemoon  - There are actually bad tone controls.  Manufacturers would implement excellent analog stages and then glue on tone controls (or headphone amps) as after-thoughts.  So, I can understand that there have been bad examples, there is also gear with consistently good examples.  Luxman for instance makes excellent transparent tone controls (but not headphone amps).