All cultures are weird as shit when you look at them from the outside.
(No, I am not excluding myself. There are plenty of people that could easily consider me weird as fuck. I rather enjoy that, so it kinda works out in the end.)
The jitsu-in is required for marriage and purchasing property.
The ginko-in is required for signing stuff as a business.
The mitome-in is required by all Japanese for signing anything.
The ginko-in and mitome-in are still required everywhere. I've never been sent an online doc that I could sign with an online service or blockchain, nor have I heard from anyone about it. It's always a letter that I have to place my mitome-in on and send back.