Yes you are right , its pretty recent inclusion of this map from flightconnections.com , the advantage is that the alliance feature is available for free through skyteam website but most other options have been disabled
If you want to filter by airline or other alliances you need to go to flightconnections (FC) , and also options such as prices are also available but you need premium version
This website has been around for couple of years , i stopped using it cause i am mostly interested by prices and thats something i can reliably get from google flights for free already and i dont need to swicth between GF and FC all the time
Not sure if it is currently 100% accurate and how up-to-date it will be maintained as routes change, but interesting nonetheless. So just flagging it up for those that might find it useful.
No its not 100% up to date but its very accurate and can give you a pretty good ovierview , usually help me spot new skyteam/star alliances routes or routes to/from airports i am interested in that i might have miss from the news websites like routesonline
and more importantly you can do a reverse search in the sense that google flights only allow you to search for origin and then leave destination field open , while FC offer you this opportunity to focus on destination and see what airlines fly there in a single shot