I agree and disagree. Mostly disagree, let me explain why.
While I agree with the idea that you "helped" by taking enemy resources, i.e. their abilities and/or aa focus helps. Its about incentive.
Remember assist give gold, and assist gold is divided among those who assist. We dont want people being rewarded by suiciding with 7% health so they can get assist gold to finish items...
We dont want people to think taking damage is something to be rewarded. Even if it has its place, even if it is useful, there are a lot of things that are useful that dont give gold. Shielding others so they take less damage is an application of an ability, something going on cooldown. Good use that helps get a kill should be rewarded. Running in and well.... @Reksee said it well:
suddenly you see a
with 0/18/57 kda...
We dont want to reward that. Giving assist make it seem like just taking damage is helping, and it probably isnt.
I see where youre coming from, but getting gold from assist should be cause you DEFINITLY ASSISTED, and not cause your potentially feeding.