I believe the main issue was preventing abuse of alt accounts 'supercharging' their own posts

Yes but that is no different from whales up-voting their own posts and pocketing the money. If it's OK in that situation why not this one?

Again I could see the abuse issue of just constantly powering up small amounts like .001 Steem

Exactly so there would need to be a minimum amount to trigger it. I think that would encourage someone like me to power up faster for sure.