Not really a '90s thing, it's actually still being done at times, even with very high profile releases. Carly Rae Jepsen, like Radiohead circa 1993-1997, was more popular (relative to other artists) in Japan than in the west, so her album Emotion was released several months earlier in Japan. And that was 2015. Usually artists don't particularly want these staggered releases to happen, it's the labels that do it to save money, because they believe they can build hype and anticipation by releasing it first in Japan, where the artist is more widely well liked and they may be able to get better sales while spending less on marketing.

But as Carly's example (weaker than expected sales) indicates, this strategy isn't as effective now as in the '90s, because every fan just downloads it illegally, and then by the time it officially drops in their country, they don't buy it.

Here's the main thing that's changed since the '90s. Release dates don't matter anymore. Mp3 sharing- let alone streaming- was not a thing yet in 1997. Almost everyone's Internet speeds were too low. If an album was released early in Japan, you'd have to either know someone traveling there, or order an expensive import, which might not even arrive in your country until your own release date, anyway.

Soon after that, college students and employees with access to higher speed internet in 1998-1999 pioneered the practice of mp3 ripping and p2p sharing, before it caught on for home users in the 2000s, with the legal iTunes store debuting for Mac computers in 2001 and finally getting big in 2004 with its Windows debut.

Anyone who tells you regular people shared and downloaded music in 1997 was not using the Internet (or possibly even alive) at that time. The capability was there, technically. But the speeds were too slow for it to be practical. Just like we technically have the ability to go to Mars- but it would be impractical until technology advances, so we don't. The term "mp3" was not even widely recognized by the general music listening public until 2000.

Fun fact: OK Computer's final release date (and, effectively, its most important, since North America was/is their largest market, and this was also the release date around the world in most places besides UK/Japan) occurred on July 1, 1997, the same day the British empire officially ended, with the transfer of Hong Kong to Chinese control.