Because:
1. The first significant agentic harness was made by Anthropic.
2. One of the most senior developers of client-side software at Anthropic is Felix Rieseberg, one of the original creators of Electron. [1]
3. After Claude Code blew up, everyone else copied Anthropic.
---
1: https://daringfireball.net/2026/07/claudes_criminally_bad_ma...
I think it also helps that it's basically the default platform for any software that AI writes, unless you tell it otherwise. And JavaScript is one of the most widely used and well known languages in the world, so there's that, too.