And very imprecise. Virtually nobody gets it right when trying to describe a relationship with an nth cousin m times removed.
And recently I tried to work out a fairly basic relationship between myself and my son's step-sisters - they're not biologically related to me at all, or even by (current) marriage, but it seemed like there should be a term for it.
Two of my cousins were adopted out, found the family as adults, and immediately had a child together. That child is now an adult, and members of his generation ask, what do we call the guy, "unclecousin"?
Languages like Polish are even worse, because you have to go in reverse, from the person described to yourself. It's the great great grandmother of the cousin of the uncle of the ex wife of your sister, not your sister's ex wife's uncle's great great grandmother.
Russian has some neat words for in-law relationships, but I'd say vast majority of the population never uses it and has to hit the dictionary when they encounter it in the literature. Which IMHO is a pity.
