Not op - answering personally.
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.