The way that it can be used for all of your needs, from development through production environments! I love being able use this in my dev environment as well at work when using our AWS instances or other cloud services where we have access with VMs etc..
It's great because you're not limited by what they provide out there (like Nagios) but also don't need something like Zabbix if their service doesn't do everything needed/wanted either - so no extra cost / maintenance required then having 2 tools just seems unnecessary sometimes especially since most things are already covered under one tool such as vector itself :).