Automatically enter party member instance

So this situation happens almost every time and it's getting quite annoying:

1)Player X sells an item
2)Player Y wishes to buy that item and joins X's party
3)Both players go to Act 1 normal to trade
4)Somehow they both end up in different instances of A1n and can't trade
5)Player X goes to coast and tries to re-enter A1n
6)Upon re-entering A1n, player Y decides to go to coast aswell
7)Now player Y is in the coast, but player X is in A1n
8)Repeat steps 4,5,6,7 until one player gets angry and leaves

The solution would consist of two parts:
1. Joining correct instance before opening new area.
2. Joining correct instance before joining a party. (in case both players were in the same area already)

Before opening new area:
1. Loop through all party members
2. If a party member is inside an area that we are trying to visit, then open his instance.

Before joining a party:
1. Loop through all party members
2. If a party member is in the same area as we are, then open his instance.

Thats it! wasn't that easy?
That is like what, 10 lines of code?
I can't see the reasoning behind not implementing this feature during the past 3 years of PoE.