We are having a pool put in. The yard is slightly sloped, so one side of the pool has boulders stacked right on the concrete edge acting as a retaining wall, which continues past the pool edge on both sides (the shallow end and the deep end) with a boulder retaining wall laid right on the ground. 

The rocks on the pool edge look nice. They are mortared in place and have pointing between the boulders. There is no mortar on any of the rocks to either side of the pool, as the landscaper said that would be a bad idea since they move slightly as the earth settles, etc. That makes sense to me. 

But as I poke around online, most of the rock walls I see folks building start with a foundation of stones dug and tamped into the ground. Our rocks are just laid on the dirt, and seemingly a bit haphazardly at that. Some of them are already moving and the jobs not even done. I feel bad complaining about the placement because it's very hard work, and getting to them is even more difficult now that the fence is going up, but I'm worried they aren't going to look good. 

Is it a problem that there is no foundation? Also, is it possible to mortar and point the rest of the wall later, say next year, after the earth around them has done what it's going to do? Thanks in advance.

Does a boulder retaining wall need to have a foundation?