Japan went through a significant cultural upheaval during the Meiji restoration. So much of Japanese culture comes from the Meiji era up into the start of the Taisho era and as a result a lot of people treat everything prior to the Meiji restoration as "ancient times".

Hell unlike most western culture, Japan didn't really get their current system for naming individuals and families until the 1870s.

But as to why all these practices in Japan that date past the Meiji era are considered "ancient", one of the major parts of the restoration was the systematic centralisation of Japanese society and standardisation of practices. This resulted in a lot of practices being more or less outlawed with the surviving practices that weren't officially sanctioned by the central government surviving solely due to rebellious/non-compliant individuals secretly preserving their practices throughout the Meiji era.

Into the late Taisho and early Showa era, the threats of violence from the central government were removed and the stigma around these "outlawed" practices faded, allowing families to publicly practice their "non-standardised" crafts.

This is more or less the reason behind the seemingly endless quantity of "ancient crafts" and "secrets passed down through generations". There was a systematic attempt at eliminating non-conformant practices for a good ~40-60 years. That's at least a few generations who grew up fearing retribution for practicing their family traditions.

There's also a whole orientalisation/fetishisation of Japanese things and concepts. The same applies to the broader east asian and greater asian cultures.