Why is feasible meeting alone insufficient under the stricter condition?

Muʿanʿan Transmission: Possible Meeting, Evidence of Hearing, and Continuity

• Even proof of one meeting is insufficient; each particular text needs explicit hearing
• It regards contemporaneity and precision as wholly irrelevant
• It requires credible evidence of at least one actual meeting or hearing between the two narrators
• It presumes connection even where non-meeting has been established