No, i just didn't like the wording in the original post mentioning all 'modern workloads' , while ubiquitous thing like cookies in httpclient is still not according to 8 year old standard. Does it make any sense now?
If your whole reason for not using .Net Core is based around this weird and honestly unimportant edge case, all that tells me is that you have a strange bias against the framework for some other reason and looking to nitpick.
And yes the HttpClient is modern. Your entire argument so far has been a single RFC issue that is labeled up-for-grabs because it's so minor and doesn't really affect anyone. Claiming the http functionality and the whole stack isn't modern because of it just doesn't add up.