Where before a very attractive person might only have access to the people in their friend group/workspace/etc and wind up settling/sleeping with/marrying one of them, now they can expand beyond that and literally shoot to the top of the gene/status pool, e.g. a very attractive girl might date a professional basketball player instead of the cute guy in the office.
This can happen on a smaller scale as well because of things like Tinder. Why date the amiable and friendly but 6/10 coworker when there is a rich, successful, charming 9/10 down the block.
Even if people are not doing this they might not be partnering up as much because of the possibility of it happening. FOMO is constant in relationship these days, IMO.