While I kind of agree with you, I have to add a few things. Especially concerning the startup culture in Japan. Yes, it is looked down upon by most, however, it exists. Compared to SV or London or Berlin it is fairly small, but it is there.

However, the exposure they get is very limited. It seems to be somewhat shut-off, mainly caused by a language barrier. Nearly everything is in Japanese, with little incentive to go international. Also, many people do not understand english well enough to participate in international communities or do not feel the urge to.

For example, look at mixi (it's a social network with roughly 15m members in japan, exists for i think 7 years+, mixi.jp), they had a huge userbase before facebook was popular in japan, even before facebook was really popular anywhere. however, their website is still only in japanese and to sign-up, you have to have a japanese cell phone email-address (for account confirmation). They are artificially locking people out and considering that japanese people increasingly go abroad/have friends outside of Japan, they migrate to facebook. Still, mixi does not move.

What I think is missing, is obviously the acceptance, as you mentioned, but also the incentive to go international(, unless the service involves billing). It's the internet and not a local sweets shop. By the way, there are also Japanese investors looking for startup and there are websites where they exchange ideas and whatnot, but it is all in Japanese.