Could you please help me understand the basis for your point of view? Precisely what evidence are you referring to? For example, the subreddit on it seems quite small... and many of the people I know could benefit from it have never heard of it before.

The first time I really heard of it was about a year ago, and there has been an explosion in tools and articles about it. No new innovation will reach mass market adoption in that time, but Zettelkasten is well on its way.