what happens when a theocracy with the potential resources that they have is allowed to spread totally unchecked?

That's hard to say, as they aren't unchecked... they may have been for a while, due to the fact that groups that are now checking them, were for quite a while on the USs terrorist list, and just as hotly pursued with US manufactured ordinance. That seems to have changed recently, as the US government appears to have realised that just because a group has an issue with a US supported dictatorship, it doesn't mean the group actually dislikes the US... per see, and that group could really be an ally if the US woke up to itself.

It also needs to be noted that groups like ISIS/ISIL exist as a direct result of US action in the area. It's unlikely they would now exist, if the US had not invaded Iraq, as the core of ISIS/ISIL is Iraqi Baathists.

Once again I don't see any apologist rhetoric in support of ISIS/ISIL, what I see is debunking of US government and main stream media claims that ISIS/ISIL is a direct and existential to the people of the US, which clearly it is not. It is a potential threat, that can become manifest, if the US government doesn't deal with it in an appropriate manner, and so far I have seen little of that, what I have seen is a hell of a lot of fear mongering, that directly feeds into Islamaphobia, with the wrong people being targeted, thus potentially, and actually (in that part of the world) causing support for such groups.

The fact is the cartels are an existential threat, whether you personally feel threatened or not. In the same way that seismic activity in New Zealand is, and was for me, an existential threat, no matter how little I personally felt threatened by it.