Because Obsidian failed to implement fast travel markers in a practical manner.
Another example, why the hell does Coyote Tail Ridge need to have a map marker?
I get that it has something to do with Boone but it has absolutely nothing around it, there's a bush of that honey mequite crap to the west around 5 meters from it, but that's it.
There's no reason to have a map marker for it.
All these crap map markers made exploring completely unrewarding.
Why the hell does the Powder Ganger camps need to have map markers?
Why the hell does Lone Wolf Radio need a map marker? If it hadn't had one then it'd have been an actual reward to find the place and to find a skill book no less.
Why the hell does Primm Pass need a map marker? If it hadn't had one then the Deathclaw could have been removed and a shortcut could be rewarded to the players that actually explore.
Exploration in New Vegas svcked, far too many map markers, I didn't explore with my eyes on the landscape, I explored by looking at that damn compass, which I can't remove in the options menu.
And the ones that place you "outside" of places? Even more horrible.
The reason I don't use the Lucky 38 as a house is because I refuse to go through 3 loading screens.
Oh how I wish I had had a mod to remove around 80% of the map markers during my first playthrough.

Might have made exploring places and finding great loot fun.