In the 1920s-30s, the world's largest corporations used nearly unlimited resources and the best engineers around to design almost all loudspeaker types we use today.
Some from that era are still considered to be wonderful sounding and are highly desired today.
http://www.audioheritage.org/html/profiles/lmco/shearer.htm
https://www.martinlogan.com/en/electrostatic-loudspeaker-history
An excellent post that supports what many of us have been saying.
High performance loudspeakers were already capable of great performance decades and decades ago.
The main area targeted by research nowadays seems to be focused around designs that are considered to be 'domestically acceptable'.
For sure, many of us here are prepared to sacrifice a certain amount of domestic acceptability (if not quite the Shearer Horn) for sonic gain, but evidently the vast majority of loudspeaker buyers are not.
Perhaps therein lies the problem as it's difficult to see how relatively small slim tower speakers can ever sound as good as some of the behemoth designs featured in the 2 websites linked above.
The fact that some of these new designs, despite the size constraints, have even gotten fairly close is a testament towards some of the design breakthroughs we have seen in the last few decades.
Especially when set up carefully in a sympathetic room with a sympathetic system driving them.