On some level this is certainly the case. the mid 20th Century, Hong Kong and mainland lineages all emphasize some form of chi-sau to the point that we assume that Wing Chun was always that way. But Wing Chun evolved from earlier fighting arts. Those old "proto-wing chun" systems (perhaps influenced by southern Hakka systems and/or Yongchun baihe) may have also had some "sticking" type drills, but probably not emphasized to the same degree. And even earlier, ancestral fighting forms likely had no chi-sau at all.
So
yes, originally, chi-sau was probably not a part of the Wing Chun martial heritage. And perhaps, in many schools today, Chi-Sau has become so hyper-refined and over-emphasized that it actually
detracts from the fighting functionality of the art.
With my little club, I admit that work entirely
too much chi-sau, and not enough sparring and physical training to reach optimal functionality. As I tell my students, this is because
it is what I enjoy. If they really want to fight well, they can (and should) seek out additional and more diverse training to address these deficits. They need to spar and work with diverse opponents and they need some foundation in grappling beyond what I address.
I've been told that such advice is "breaking my rice-bowl. I cal BS. Why not give honest advice?. After all, I don't teach this to make a living.
Still I have to be dicreet. Our WT-offshoot association preaches that this chi-sau heavy format is the secret to real and complete martial mastery. And they take Chi-sau way beyond what I can do, teaching dozens and dozens of complex "Chi-Sau Sections" or routines that solve all kinds of "energy puzzles". Practicing these endless, interwoven patterns has pretty much become the core of their intermediate to advanced curriculum. And frankly, although intricate and fascinating, I find that it has become a rabbit hole that ultimately leads away from realistic fighting skill.
Hey
Yak Sau and all you other WT lineage guys, whattya say? As Dennis Hopper's character said to Christopher Walkin's mobster in
True Romance, "Am I lying?"