This is kinda odd, it seems as though clade focuses only on lineage and not really biology.
Well, yes and no. Clade is
defined by lineage. But it turns out to be a powerful concept about the rest of biology. That's why it's such a good idea.
Your comment is as though you said: "This is kinda odd, it seems as though the periodic table focuses only on proton number and not really chemical properties".
Now, in a sense this is a true thing to say about the periodic table. But it rather misses the point. Because it so happens that we live in a universe where proton number is the key to chemistry. Sure, we can
imagine a universe where this was not the case, and then ordering elements according to their proton number would be lame and silly. But as it happens we do not live in that universe. We live in one where the proton number is
the crucial piece of information about an atom.
In the same way, we can
imagine a universe in which birds were descended from cows as well as from archosaurs. And if that was the case, then the concept of a clade might not be much use to biologists. But it so happens that we live in a universe where the concept
is useful. It so happens that arranging species in clades does indeed provide us with insights into the biology of the species. And this is why it's a good idea.
Edited by Dr Adequate, : No reason given.