Some of these items have been in the same medium for as much as five years or more without any evidence of salt buildup. Tree bark that is in chunks. Orchid growers use it for growing medium for their lovely flowering plants. Over the years it rots and fills in the air gaps. It also stores moisture and nutrients and is a growing medium for beneficial soil fungi.
Roots seem to like it because they grow into the bark chunks.
You can observe the bark chunks dangling from the roots while root pruning. There may be substances in the bark that suppress root growth. I intend to use only composted bark from now on. Composted wood chips. I use what is available to me.