This seems to me (as do most audio discussions) a bit like the old Miller Lite commercials. Tastes great! No, it’s less filling! There are many ways to skin the audio cat so I say to each his own.
For instance Decware’s OB which uses the Lii 15” full range in a simple baffle does not (as far as I know) use a crossover. Now I sure wouldn’t pay $5000 and wait forever for a pair but they seem to be selling them so who am I to say they are wrong?
This is a shame, just a reason to charge a hi price ticket for this assembled model. They have a 12'' FR brother from this 12'' woofer, but was used the different 10'' FR to profit more. 
Crossoverless FR drivers are the max fidelity possible but they are not profitable to the manufacturers, the price is too low, F-15 for just $399 pair.
The speaker referenced above uses a 15” woofer not a 12” woofer. And at $4300 it may be considered high priced to some and not by others. Compared to the speaker I mentioned above I would say it’s a bargain.
Additionally Lii Song freely shares the development, construction drawings and serial crossover schematic for those that want to go the DIY route.
http://www.modelpromo.nl/audio-dandy/reviews/The%20Liiondias%20Open%20Baffle%20Speaker/The%20Liionidas%20Open%20Baffle%20speaker.pdfI wish everyone good listening wether they use a crossover or not.
