Purely anecdotal evidence, but Julia's support for basic HTTPS server capabilities is immature at best. Sure, it is capable, but the amount of effort to build an web API is much higher than in a language like Python which has had many more years to mature its ecosystem.

That's not to say I dislike Julia. I think it's a wonderful language for numerical computing. Over the next few years I certainly hope to see wider adoption among data science and analytics communities.