Yeah Disney Plus seems to define "MCU" as "Marvel Studios", which I think is fine. The shows aren't "essential viewing" for the overall MCU story. Even if they end up including characters from the shows in the movies, I'm sure it will be done in such a way that the audience doesn't need to go back and watch several seasons of one or more shows to understand what's happening. So I think it's fine that D+ isn't including the shows under the MCU banner.Neither is Agent Carter, which we know is canon.
It's because they're not Marvel Studios content, not a message on canonicity. It's the brand, not the universe.
Even then, Disney+ think Iron Man 3 takes place after Thor: The Dark World, so they clearly aren't that reliable.