The moment you have an audience for something it significantly changes the experience. Doesn't matter if it's music, development, cooking... if other humans are involved on the receiving end it makes it different.
For a lot of us, we're very protective of our creative endeavors. And, lots of the time the journey we're taking is one of vulnerability (learning, creatively extending ourselves, taking risks).
Then there's the criticism and critique. People can objectively be pretty awful. It doesn't matter if it's making my own software tooling, or a song, or fleshing out a new idea... I just don't want to hear anyone's opinion - I want to focus on being productive in what I'm doing. I've often found that isolating is way more productive than trying to ship to an audience. If I need other people I don't pull them in as an audience, I pull them in as an advisor and/or teacher: contracting out a code review, or going to guitar lessons.
If/when this stuff I created dies with me that's OK. I'm a fart in the wind anyway, and I don't care about silly things like "legacy" - I just need to create stuff to optimize and improve the world around me. And, sometimes I create stuff just because it feels good. It's a selfish endeavor sure, but I'd have it no other way.
I was going to reply but you summed it up nicely. I have been polishing away on a dozen or so personal software projects, but I never release them publicly, don't use GitHub, don't even blog about them. I'm at a point in my life where I don't need/crave feedback or validation or attention or whatever drives people to constantly need moar audience for their blog and moar downloads for their software. I write software because I enjoy the act and it solves problems that I encounter.
Not releasing means I don't have pressure to keep them compiling with the latest SDK, I don't have pressure to port them to Windows, I don't have to respond to requests from users or other developers, and I can feel free to use the codebase(s) to learn and explore the boundaries of my knowledge and skills, without public scrutiny and bikeshedding.
There is also something to getting you software to a level where you show it to others (the sooner the better). If you don't showcase your stuff odds are people won't find it.
But I'm not going to do that. So there is some associated pain. But it's diminishing with time.
And the attention my project got is definitely greater than zero. And the internet is forever. So there is a kind of peace.