I would have to agree that immersion these days is kind of non-existent in most cases, even with some of the bigger hitters. And really, it depends what you're going for.
If you want an ARG style experience, then immersion is a must. ARG's are all about the immersion, and keeping the player under a sense of "is this real, or not real". That and interaction. Though ARG's aren't for everyone, and take a lot of upkeep to keep it running and accessible. A good example would be Caught Not Sleeping, which is pretty much a Slender Man ARG in most senses.
As for visibility, most Slender Creators these days are more visible, with a shift away from the whole immersion business. In some cases it is a shame, as it loses a sense of unknown that a Slendy Series can have. But it can aid one with other factors, such as having tighter control over what you are doing, how fast you’re doing it, and keeping the story on track. If you've got a story planned out, it can make it far easier without much outside interaction. A good example would probably be StanFredrickBTS, which told its own story, whilst having series commentary on the creators OOG channel.
And whilst there is a difference between immersion and visibility, it's best to remember that In-Game and Out-Of-Game apply to your work in any case. It's best to keep your Slender works separate from any other works or channels in most cases, if only to make things tidier.