Information sharing is one of the most critical elements of any security strategy. Without it, security has to be painted with a broad brush where literally anything is possible. Being able to compare the device or network you are trying to protect against a set of threats that are known to be currently active is invaluable in pitting the right resources and countermeasures against the appropriate target.
Of course, there is much more to threat intelligence than simply being able to block a known threat using an updated edge or endpoint security device. While prevention is critical, the challenge with spending most of your security resources on building a stronger front gate is that you only get one chance to get it right. If an attacker manages to get past that defense, and they will, far too many organizations have limited insight or protections to defend against an attack moving laterally across your network.