This also supposes that ancoms and an-markets are 'enemies'. I think they are simply different ways to interact with their communities. At the end of the day, they are both about resource allocation and the methods to facilitate such. If you have an enemy simply based on how they choose to trade and allocate their resources with others... well, that's kind of a petty thing to have an enemy over.

The fear between the coms and caps is the same on both sides: that one will use their system of resource allocation to force the other to abide by their own preferred system. It's assumed that one will try to FORCE the other.
If you believe, first, in voluntary, consentual interactions and exchanges, then you recognize this can't be done by either side and any attempt to do so would be rightly met with defensive force.