Sending alerts from Kapacitor via MQTT allows users to bypass the need for a Node-Red instance and send color-coded alerts directly to an MQTT broker. This is achieved by editing the kapacitor.conf file, creating a new TICK script in Chronograf, and using template variables to map temperature values to corresponding colors. The process involves triggering an alert when the change in temperature exceeds a certain threshold, and then posting the resulting message to the MQTT broker under a specific topic. With this setup, users can send alerts from Kapacitor directly to their MQTT broker without relying on external services or JavaScript transformations.