A middle length riddle

You wouldn't be here without me
I am feared by many
and obsessed over by some
I can purify you by shocking you with an ordeal
People might call me amicable but you should stay away from me
If your roots run deep you may be born of me

Who or what am I?

Filling out lines 5, 6, 7 & 9 (Raul Torry has been confirmed correct for all others):
People might call me amicable but you should stay away from me

Friendly Fire - a nice-sounding name for something you absolutely do not want to experience. (hagfy was first with this after translating their comment)

I end your friendships (I don't believe I've got this one right)

A 'Flame War', as in an internet discussion gone off the rails ...not really an example of a friendship, I know.

I can be your end

You can be 'Fired' from a job.

If your roots run deep you may be born of me

Forest fires pave the way for new growth, with deep roots being safe from the blaze on the surface. (following Rubio's link, I see they were first)

I think you are:

The fire

You wouldn't be here without me

Human beings depend on fire to live.

I am feared by many

Many people are afraid of fire

and obsessed over by some

And others love it. (Pyromania)

I can purify you by shocking you with an ordeal

Fire is used in rituals to purify

People might call me amicable but you should stay away from me

Most people know how to handle it, but sometimes it can get out of control

Fire can kill your friends in a fire

Or even you