Imagine you have a household with 2 adults and 2 kids, and you’ve setup some level of presence tracking. You want to use automations to turn off everything if nobody is home, turn on some things if only kids are home, turn on other things if only adults are home, and turn on everything if kids and adults are home. You could build this logic into every automation you have, but it’s a lot of repeated logic to put in every time you wanna add something cool.

Blueprints mean you don’t have to write it out in every automation. But I’ve never found them to be especially convenient for updating. And they still have the automation doing all of the heavy lifting.

You could have a home State sensor that you depend on automations to manually update. But this is only as up to date as you make it, either running every so often (stale data) or using automations based on a change in presence tracking to update a sensor (buggy maybe? have not tried it but sounds prone to race conditions and misfires to me). Closer, but unideal IMO.

Or you could pull this logic into a service that returns 1 of 4 possible states - full, empty, kids, adults. Your automation no longer has any logic to figure out what the state is or who’s home, it just asks what set of rules are in effect and can apply them. This lets the automation focus on a smaller area, which means less shit that needs updating if you change something, less chance for bugs.

There’s not a ton new you can do now that you couldn’t accomplish before, but you can do it in smarter, more maintainable ways.