There's a few things at play with this (and no, it's not you).
It depends on the type of job, but my hypothesis is that there are two driving factors:
1) It's a seller's market. Yes, things were transiently not as bad the last couple years as they normally have been, but "not as bad" for RadOnc is still...too many RadOncs.
The cost to hiring comes in two forms - both time and money. If you want to fill a job, weeding through a ton of candidates to find some you like is a time/energy-intense process. Once you find a handful, it's A LOT cheaper to spend the money to fly them out and see who you like most vs repeating the entire process from square one if you only bring out your favorite candidate, one at a time.
Part of "ghosting" is keeping your options open. If they interviewed 3 people, and extended the offer to one - they want to keep their "backup options" on the hook as long as possible. Ghosting is unprofessional, sure...but it works.
But ghosting in this context is also tied to my second factor:
2) Most humans have no ability to navigate conflict and avoid it at all costs.
Telling someone "hey, nice to meet you and your lovely family, but we actually don't like you as much as we like someone else, so bye bye forever, have a nice life".
Much easier to never say anything at all!