And what is the actual explanation that actually makes sense (apart from profit increase)?
I have booked flights A->B->C and got down at B because that was cheaper than booking A->B only. Not sure where this all makes sense at all.
The full explanation would take a wall of text (and still let you unconvinced because you feel entitled to do as you please, probably).
Super-condensed version: civilian flight are a pretty difficult "product" to handle efficiently. Price increases until 1 minute before closing the airplane doors, then falls to zero. On top of that, the product "provider" also needs its own product in order to move personnel and technicians all over the globe, but of course they cannot just cannibalize their own products beyond the point of profitability.
Plus they have to handle rebookings and passenger protection in cases like delays, sudden airport close-down and so on. (Have you ever been on a waiting list, btw?).
All this is pretty complicated to manage already, so they need to exert as much control as possible on yield and occupancy.
TL;DR: a flight is not a bus ride. So if you just decide to cut it short the airline will try to reuse your vacant space for whatever reason.
It’s called “skip lagging”. The airline can possibly try to collect money and if you do it often, ban you from flying with them.
https://www.npr.org/2023/08/23/1194998452/skiplagging-airfar...
The reason is happens is that take for instance ATL (former home). ATL is a Delta hub and has direct flights to a lot of places that other airlines don’t. Between people preferring direct flights and the lack of competition, they can charge more.
But flying out of MCO with a layover in ATl, they lose the non stop flight advantage and they have to compete with other airlines.
Also ATL sees a lot more price insensitive business travelers than MCO. Businesses aren’t going to force their salespeople and consultants on one of the low cost carriers.
It seems to me that since airlines can't force you on a plane except for taking your luggage hostage, you're free to drop as long of a 'tail' as you wish. I'm wondering whether they'd put you on a black list or something for doing this consistently.