I never took it so literally. Just thought it was to develop a relationship with a mark and then put the screws to them as soon as possible.
Someone gullible, like a reality show contestant (90 Day Fiancé, Bachelor, etc). A person who can “fall in love” immediately and will do whatever to prove their affection because they believe they have limited alternatives.
A year investment…that is a meaningful (platonic or romantic) time for a relationship, where some sense of obligation/pity to the scammer could develop.