Reasons why people GRIND rather than INSTANCE?

I'm on the Nordrassil server, which is still at low or med
population. It is like pulling teeth to find anyone to go into an
instance- PUG player or Guild member.

I love instances and dont understand why people say, "Can't come, i
need to level my character tonight."

Grinding by yourself really SUCKS. I'm level 57 now and really hope I
dont have to grind 13 levels by myself just to get to the point where
i can play with other people. I'm considering a new guild or even
server to remedy this problem.

I've even considered just ditching WoW due to this issue.

They usually cite that grinding solo is most efficient way to get XP.

With a group of level-matched players, it's pretty easy to get upwards
of 4-5 bubbles in an instance run. I've gotten up to half my bubbles
in Scarlet Monastery when I ran it a time when i was about 2-3 levels
too low to really be there.

Anyone have same findings?

Solutions?

.