Do they though? All things considered the scope of the game seems very small and the stakes quite low. I myself didn't realise this until I did a non canon path where I engaged with the elves. The conversation with bitch elf lady at the end basically implies that the Templars and Elves are just 2 tiny little factions with access to a hidden secret and some cool toys. Like groups of children fighting each other with sticks and stones at the kindergarten recess, over control of the single water fountain
The elves aren't a threat to humanity. She says so herself. They don't have the numbers. Not even remotely. If they waged war, they'd be all but wiped out in a few months. They are only a threat to the Templars and who gives a shit about them? They could all die today for all I care, honestly.
We still don't know much about the Hellspawn or the other races/worlds that connect to Neverwhere. Maybe those could pose a threat to humanity, the elves or even Neverwhere eventually. As of right now, from my perspective, it really seems like a tiny scale conflict.