I didn't specifically say that no one knew about comb filtering, or that using dirt cheap drivers would produce high quality arrays. I only used these as small examples. Those DIYers who live in the high end world of $250 Revelator tweeters will certainly not agree. I said that there appears to be a general lack of understanding of the elements of array design in the general population of speaker builders. Those with specific EE degrees who specialize in speaker design are usually aware of these issues. Speaker designers whose whole job is designing speakers may or may not be aware of the special characteristics of array speakers---even those with a huge amount of knowledge in the field.
Russell is a giant in the field and his interpretation of comb filtering as posted in a previous item here, as well as his 2005 array suggests that all of this is pretty new to him(the array is nice, but it looks like something that was available both commercial and DIY, some time before 2005).
It was a generalized comment. Individuals may be in communication with a more enlightened group, I envy them.
This group IS EXCEPTED FROM THE OBSERVATION!!!
Pinky