Red did have a question about it which I've tried to answer myself:
In a highly deflationary environment lenders would lend money at negative interest rates and still make a real profit.
This seems quite silly as opposed to not lending the money and making even more real profit.
Perhaps I don't understand what you are saying?
If everyone just hoards the economy stagnates. By lending out bitcoins it is possible to stimulate growth in the economy.
As a simple example:
Say 1 bitcoin buys you 1 loaf of bread, and the entire economy is based on comparisons to loaves of bread.
Scenario 1:
At the start of the year I have 1000 bitcoins, I lend out 100 for 1 year at -50% interest.
This stimulates the economy to grow 100%
At the end of the year, I will have 950 bitcoins, but they are worth 1900 loaves of bread.
Scenario 2:
1000 bitcoins, I lend out 0.
The economy doesn't grow at all,
At the end of the year, I will have 1000 bitcoins, but they are still only worth 1000 loaves of bread.
There is a lot more math you can do to cover more complex scenarios and make more acurate estimates of growth, but I think this illustrates the general principle.