I would say infinitely moreso for streamers because they can and often do put hundreds or thousands of people at the scene of a crime, or event, which dwarfs the number of scanner owner/enthusiasts who might be in the area listening in.
At an APCO conference a few years back, one agency used a very specific situation to explain why they went encrypted:
Live shooter at a local high school.
Officers from all adjoining jurisdictions rush to the scene.
Some yahoo is doing a play by play on social media.
Hundreds of concerned parents rush to the scene to retrieve their children (I can understand this, I'm a parent).
Situation at the school is still active. Live shooter hasn't been apprehended.
Now a few hundred parents show up and try to rush the school to get their kids. Most of the officers on scene are now pressed into crowd control, keeping parents out of the scene. That slowed down response.
I get it, I'm a parent, but the person posting all this play by play on social media changed the dynamics of the situation.
That very situation was the reason said agency went fully encrypted. Officers needed to be doing their jobs, not tied up with crowd control.
It wouldn't be necessary to encrypt without an audience, would it?
If there was zero audience and all information shared over the radio was guaranteed to be secure, then no. But remember, it goes back to basic IT security standards.