New accounts cannot perform transactions because there is no existing "bandwidth" the account has which basically is the requirement needed to perform a transaction (creating a post, commenting, resteeming, or upvoting, etc.). Without Steempower (vest), a user cannot perform such actions.
The account is technically disabled. To make it active, there's a delegation needed (atleast 1 SP) to perform transactions and make the account active. The SP delegation is actually the reason why account signups takes so much time because they are manually reviewing all of the accounts pending for review.
However, there are only 5 days left before HF20 gets launched so allow me to spill some beans here. New account created doesn't have a startup "Steempower" anymore. The account creation (which was 3 Steem) will get burned via "@null" account. However, the Resource Credits gets intact with the user because of the 3 Steem account creation fee.