Probably because node imcompat / fresh start wasn't the only key differentiator for them?? Bun also had/has (in context of a leg up over node and similar to deno):

- typescript support - built in linting - built in package manager command - built in transpiler/bundler

Yes, I used Deno because it had an interesting approach to permissions, dependencies, etc.

Once it become “a drop-in for Node”, I decided why would I not use the more popular drop-in for Node that has a bunch of other interesting features.

Bun also had far better compatibility with many libraries & native dependencies

Presumably they like other aspects of Bun, in a world where a clean API is not an option.