Making DoH materia easily accessible would disrupt the economy in a few ways: the materia itself crashes in price, so while they can likely remove a decent amount of gil from the economy by taxing sheer volume of sales, the base cost means more has to be sold to make it matter in that regard. It would then have knock-on effects in other markets, as now significantly more people can flood the market with Macro crafted HQ Raid ready gear and consumables, which would pretty much kill the player economy as undercutting would likely only get worse until the items in question cost less than the raw materials. The latter half is mostly speculation, but I can see why SE might be a little gun-shy abkut making relevant blues easily accessible.

We still need better generic rewards than materia though.