There are several factors to consider:
1) Many places simply, honestly, just don't know any better. Most stores I see selling such Linckia have about the same amount of information, sad to say.
2) Stores are out to sell animals, not discourage their keeping (in this respect, I give SWF some kudos for providing a forum for feedback). However I always keep this in mind when selecting animals - their advice, by definition really, is not necessarily objective.
3) These animals are very delicate shippers, and many (perhaps most) are doomed the moment they are collected as they are unable in many cases to adapt to synthetic salt mixes.
4) "success" is relative. Many people believe these animals are short lived, so keeping them 6 months to a year is considered normal and hence they are easy to keep.
Very misleading I am afraid.