I know cURL does 1001 other things too, so the two tools aren't really in competition. HTTPie is more akin to Postman or Insomnia.
curl 'https://raw.githubusercontent.com/LearnWebCode/json-example/... | jq '.'
There has been some work recently to make the interpreter start faster. I hope we will see the result in Python 3.7.
1. By default curl doesn't follow redirects and I think most use-cases (not all) require that behavior (at least from the cli).
2. Similar to wget, many users who start using curl do it to download something, probably a file. But opposite to wget curl doesn't write a file but to stdout. Actually, I find curls behavior much more UNIX style, but it is probably the first obstacle every user has to tackle. Nevertheless, in the end this makes curl easier to use, because you do not have to remember which parameter is used to set the output file name, but instead just use the universal unix operator '>'.
not to mention this brings windows closer and closer to nix. windows making itself more familiar to nix increases the number of ops folks that are willing to transition from nix shops to windows, increasing windows share in the server market
plus, as others have pointed out, curl handles protocols besides http.