Why is freezing conflicts considered a good thing?

Suppose there is an armed conflict in an active phase somewhere. Let's consider it from a position of a third party which doesn't sympathize with either side of the conflict and wants to minimize casualties.

Generally, such a side would call for "an immediate ceasefire", which often means freezing indefinitely a conflict without solving them. However, because a conflict is not resolved, it is likely to break out again and get bloodier, because 1. when a ceasefire is achieved, both sides will develop their armies fearing that the conflict will resume 2. new technology makes wars bloodier over time. So it seems smart, at least in some cases, to just let the conflicting parties "sort out" their conflict on the battlefield and not do any actions to stop the conflict. Why is this not proposed in practice?