I was mostly reacting to the “we did everything by chat” part.
There are countries were this is a mundane thing, and you can go through the whole process digitally, including all the contracts signing. Sadly in Japan this is far from being the norm, and the stamping culture is one of the cause among many others.
There is a good 99pi episode on this, in extreme cases people need to physically go to the office just to stamp their papers.
(otherwise making a stamp is a matter of 30 min at any shopping mall, it isn’t a barrier in any way)
Not a big deal, it plays the same role as signatures do in the US. Only very recently did we stop having to sign credit card receipts here!