All I want from Jira is to allow me to use Markdown.
I imagine this is because JIRA (2002) predates Markdown (2004), or at least its mainstream popularity when GitHub adopted it.
As an additional side note, Jira updates are NOT free. You have to pay for a license fee every year to get the updates + support, but the product unfortunately remains kind of the same: super slow and with missing basic features (e.g: Markdown)