If 5-htp causes anxiety, isn't it a little pointless to take it for depression?

Not so simple. Stimulating different 5ht receptors will have different effects. 5ht1a receptors will alleviate depression and anxiety. 5ht2a and c may induce anxiety. 5-htp stimulates all those receptors. Regardless, i agree that it's pointless to take 5-htp at all. It is unlikely to treat depression or anxiety any better than a sugar pill. Serotonin isn't the only answer and it's an incomplete one at that.
Makes sense. If you consider anxiety and depression as opposite ends of a spectrun of neurotransmitter activation, it makes sense.