I was going to publish the source of my language under GPLv3 with the linking exception.

To me it looks like an ideal option: it protects the project and its contributors, and it doesn't result in any inconveniences for companies, since a compiler is not a library that has to be linked. And of course it can be used to develop proprietary software.

But several people are confident [1] that if I don't go for a copyfree license like MIT or Apache 2, lots of developers and companies will be scared off from contributing.

I'd understand if it were a library, then most simply wouldn't be able to link it. But you don't link a compiler, and the linking exception allows to use the stdlib without any limitations.

If they want to modify the compiler, it's easier for companies to contribute rather than support their own fork any way.

And if someone really needs a copyfree license, I could always have a separate license for them.

What are the drawbacks I'm not seeing?

Thanks

[1]: https://github.com/vlang-io/V/issues/22