I'm mixed on this personally, on one hand... I get it. Having curl on the XYZ micro controller you're using for a project is good. At the same time the only reason MSVC added c99 support was community pressure because major projects said "we don't care about MSVC anymore we're moving on"[1]. So clearly there is a correlation between vendors and versions. If the vendors don't feel pressure to support newer versions then they'll just continue to ship the garbage they've been shipping for years. I personally don't have a good answer for this. Daniel very clearly has made his decision and I'll respect that as it's not my project.

[1] Also because the C++ committee ignored Herb and just forced it into later C++ revs from a library perspective.