I find that this statement may be used so people don't have to actually stick to a thing and finish said thing.
After all, God is always moving us around, never letting us get comfortable. Not even comfortable enough to finish what we started!
So I think what happens in some circumstances, is that folks always like a "fresh new thing", and they don't want to persevere in the thing they started. So in order to escape the boredom of actually finishing a task, they start a "fresh new thing" all in the name of "well God is just getting me out of my comfort zone".
What if one's comfort zone is always having to be in some "fresh new thing" as they avoid the "boredom" that comes through actually finishing a task?
Some of these thoughts come from my experiences in Christianity and church environments. I recall so many "new things God has directed us to do". Yet there was a pile behind us of supposed "new things God directed us to do" that never got completed!
It's as if people sit at the feeding trough of "the fresh new direction from God". Then when that thing isn't fresh anymore, they discard it into the pile and wait for the exciting new thing direction. All the while forgetting God gave them a bunch of "new directions" already. "New directions" they never followed, and never completed.
So it's really just "the next big thing" mentality transferred into the Christian context.
In reality our faith has teachings that aren't "new". We learn from the faith that has once been passed down. But that's not fresh and exciting, so we need to invent a thing called a comfort zone to justify getting away from this stuff that's been taught for thousands of years.
Jude 1:3
3 Beloved, although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints.