Pretty much. I became exposed to T6 5w-40 from the Subaru world as it was an alternative to the oem spec'd 5w-30. At the time, the talk was how 5w-30 sheared and burn off, so the simplest, easily available alternative was T6. If you were really into Euro oil's, it was the green savior of Castrol 0w-30. I ran T6 in my Subaru and never had a problem. But today, I would just pick one of the many flavors of 0w/5w-40 available everywhere.
T6 being intended as a mixed fleet oil (at least the S rated versions) it has its purpose in gas engines too. But really comes down to application. These mixed fleets are primarily used for work where there's idling, normal driving to work sites, hauling, etc.; applications that don't usually see high rpms. And of course there's the added benefit to the operators of simplified maintenance/costs within the fleet.