Have speakers really improved within the last 20 years??

First of all let’s start with a definition. 
Paranoid personality disorder (PPD) is a mental illness characterized by paranoid delusions, and a pervasive, long-standing suspiciousness and generalized mistrust of others. People with this personality disorder may be hypersensitive, easily insulted, and habitually relate to the world by vigilant scanning of the environment for clues or suggestions that may validate their fears or biases. They are eager observers. 

They tend to be guarded and suspicious and have quite constricted emotional lives. Their reduced capacity for meaningful emotional involvement and the general pattern of isolated withdrawal often lend a quality of schizoid isolation to their life experience. People with PPD may have a tendency to bear grudges, suspiciousness, tendency to interpret others' actions as hostile, persistent tendency to self-reference, or a tenacious sense of personal right. Patients with this disorder can also have significant comorbidity with other personality disorders (such as schizotypal, schizoid, narcissistic, avoidant and borderline).

Please prove to me irrefutably that you don’t suffer from the above. Every single one of your thread starters demonstrates suspiciousness and generalised mistrust in the industry. A tenacious sense of personal right. And zero emotional involvement. 

Which takes me to the next point. Psychoacoustics. Music. Sound reproduction. The objective sound wave and the PERCEPTION, the emotion derived. I am not a microphone, an oscilloscope, an instrument. I react emotionally to the music played through my system. Please quantify emotion, quantity and quality. 

I can’t quantify perception. I can only tell you that I take more enjoyment in listening to system A compared to system B. 
A Benchmark DAC measures perfectly. And yet many people dislike (or take little pleasure) in listening to that sterile, hyper-detailed studio sound and prefer NOS, valves or any number of technologies that might not measure as well but are perceived by their owners, in their systems, as more satisfying. 
Which brings me to point three. System. You can’t  judge speakers in isolation. The speakers are placed in a unique room.  They are connected through long wires to an amplifier. The amplifier to a source. Everything is connected to the mains. The mains matter. The electronics and wires matter. The room is almost as important as the speakers themselves and there is no telling how speakers are going to perform in a given acoustic space. 
If you would even begin to grasp the complexity of the answer to your question, involving architecture, physics and psychology, you would know better. 
Last but not least. People on this forum don’t obsess about absolute quantities or qualities. They take pleasure in this hobby and follow their own tastes and preferences. I buy a new set of speakers not because they measure better, but because I LIKE what I hear, in my room, with my electronics. 
Tastes also change in time, possibly in line with the physiology of perception. We have a much better hearing in our twenties than in our sixties. Much of the high frequency range is lost as our ear ages. I have seen, time and time again, people starting their journey with detailed, transparent solid state systems and ending up favouring a seductive, warm, valve glow. 
Very little in this hobby is quantifiable. In fact I would go further and say, this hobby is not an exact science at all and numbers are the least important measure of it. You can obsess about demonstrating X W or Z until your hearing is reduced to tinnitus. Or you can just find a good enough system to enjoy the music. 
I enjoy my system now than the one I had 20 years ago. And that is all that matters to me. 

A perfectly fine speaker twenty years ago is still a perfectly fine speaker.