Very true. Some of us actually go to the trouble of hitting the Japanese search engines or going through Japanese phone books and the like. All the fun of a treasure hunt, playing Junior G-man, and perhaps the chance to do a good deed into the bargain.
But people practically never post anything resembling a clue.
Things that would help tremendously:
1. Name, of course. And this being Japan, the KANJI, if you know it. Especially for first names.
2. Name of any and all other family members that may have a phone listing. It may be necessary or expedient to go through another relative to find the target, if it is impossible to find a listing under their own name.
3. Last known address, or as much of it as you know. The more specific you can be, the better. It's no fun digging through the white page listings for an entire prefecture hunting a needle that may or may not be in the haystack. I've done it before, trust me on this.
Barring this sort of thing, the very few people on the forum who have the time, ability, inclination, and access to resources to actually be of practical help are very likely to just totally ignore the request for info rather than for the umpteenth time type up a post asking the seeker to post the info. Since they seldom come across with anything anyway, more and more nobody even bothers.