One of the biggest hurdles we face is getting new accounts registered without spamming the network. The cost to register an account is about $0.01 and to grab new users we require going through 3rd party centralized services to help people register their account. This harms the whole experience.
I would like to propose we allow new accounts to be registered in exchange for a "proof of waste" of $0.01. A CPU burning 100W for 1 hour at $0.10/KWH would do the trick.
From a user experience point of view it would be "slow" compared to using a centralized service would could verify your email in 5 minutes... but the centralized services would cost the network more than $0.01 per user to operate. This would then have to be paid for via delegate pay.
A solid user acquisition plan would easily handle the registration for the user and $0.01 trx fee is likely nothing compared to the value of signing up a user. So perhaps the entire the POW registration has no effective value.