It can if you initially wrote your code to use WinHTTP

In my experience it matters greatly who writes the quite early code for a project. The Windows development environment* in particular really encourages people to write code that's completely non-portable. So one "Windows" guy writing the core of a project can build into it a great many non-portable assumptions, without a hint of malice on their part. It's just natural to them to assume that strings are UTF-16, and a long is 32-bit, and you should write certain things with a leading underscore or in all capitals when that only actually works if you have Windows header files...

Lots of crazy decisions happen when there's only one or two people working on a project, perhaps before it formally exists at all. And it's tough to come onto someone else's project and start ripping out reliance on perfectly good APIs whose only fault is that they don't exist outside Windows. It can give people who do spend all or most of their development effort on Windows the impression that you're just jealous - that Windows has these features, and other platforms don't (when in reality often they do, but with a different API) and so really you ought to just give up on those also-ran platforms instead of insisting on portability.

* Everything from Visual Studio tools, through magazine articles, live training courses, KB articles, almost all of it is written with the unspoken assumption that portability outside Windows is irrelevant.