your research question is a paradox. a lot of old currencies are proof of work and harm the problem a lot as the more power you consume the more u earn. then newer ones do proof of stake or in steem witnessing. now mining is often done by asiic miners but vericoin/verium just reduced the difficulty and made it only slowly cpu minable. inflation of the coin can reward ur targets, like steem inflates to reward content creators. but why would someone keep a dwindeling investment in a coin when they could just donate it. then usres are not rewarded.