Guild Wars 2

Basically as the title says, yet they can buy all other gem store items, but not these two.

Because that’s something that ANet has decided is a perk of buying the game.

Just because it can’t be abused by gold sellers or trolls doesn’t mean that ANet has to let players have access to it.

How would gold sellers abuse the airship pass or home portal,?

At a guess because f2p are restricted on their movements as to what maps they can go to and these can allow them to bypass these restrictions.

Central Tyria (Core) Maps & Content: Starter maps only until character reaches level 10. Lion’s Arch unlocked for each character at level 35

The Airshop gives access to Gendaren fields and the Home Portal gives access to Divinities Reach. From there they can get to Lions Arch.

They can’t. Abuse by RMTs isn’t the only reason for P4F restrictions is what is being stated.