Re: mining efficiency
It's scale that does it.
Conhive is basically a mining pools where all participants recieved a share of the block reward based on their contribution in hashes per second.
Having your own pc mining on your own your probably hitting .2kh/s at best which means the odds of you getting the block reward on your own rounds to 0. As part of a mining pool that .2kh/s might translate to a few pennies a day.
Now, if you can get thousands of machines all mining at .1kh/s all using your coin hive ID your share of the reward is much bigger!