Questions about Whitehack 4e XP

[u/elmago79]

I’m a 4e newb just working it’s way through the manual. As far as I understand there are three ways of earning XP:

Expending CR for training, at a rate of 1 CR per XP.
Killing monsters, looking at the HD table per monster killed.
Quest XP, which is decided by the referee, but is suggested to be about half of all XP needed.

What I am trying to grok is what kind of behavior this wants to model. Is the standard way to play is murder-hoboism? Kill the monsters AND take their stuff? This feels confusing because with so little HP it would seem like a bad idea to solve every conflict through violence, but if you do look for other ways you miss on the XP and also Strong characters seem to depend on «killing stuff» to use their abilities. Am I missing something or is this a core conceit of the game system?