I myself am a weeb and I've traveled to Japan 3 times so far. I've driven over 2000km there and I'm familiar with the culture. I even speak some Japanese. I considered living in Japan for a while but the long term visa situation is a major problem.
what you say is true, but you completely missed my point.
what you fail to mention is that most of those who "stay in Japan forever" do so on a spouse visa. it's the only "accessible" way to permanent* residence in Japan
Japan immigration laws are very hostile. even in America you have a way to permanent residence and even citizenship, usually all that is required is 5 or 10 years of living and working in America. Japan provides no such path to PR. Japan has even exercised their "right" to withdraw your PR status: during the pandemic many foreigners were caught outside Japan and not allowed to come back to Japan. their japanese-by-blood spouse and children, yes. this is the problem with Japanese immigration
imagine building a life there and , when Japan considers you are no longer useful, off you go.
this happened in the 90s with Brazilian-japanese that were invited to live and work in Japan somewhere in the 80s. then the bubble busted and they were basically deported. people who had been living in Japan for over a decade and had nothing left in their home county were forced to leave for the simple fact that "Japanese immigration laws allow such a thing
*: as you can see from my previous examples, permanent residence in Japan means more " a long term visa that can be cancelled on a whim".
(fun fact: citizenship can be acquired relatively easily. citizenship is granted by the department of justice, and not by immigration. to request Japanese citizenship you need to write a a letter, in Japanese of course, to the DOJ of Japan, stating that you have lived there for many years, paid all your taxes, have no traffic fines in the past year and you would like to become a Japanese citizen. relatively easy means there aren't a million rules for this, but it's up to the judge's opinion)