Monthly NAV was the hedge fund norm because valuation was manual and reconciliation slow. Daily NAV requires the administrator to receive positions and cash from custodians and venues each day, price them, accrue fees and publish, which is only practical when the data flow is automated.
For investors, daily NAV means the reported value is at most a day old and that redemptions can be met without waiting for a month-end. For managers, it means fees and performance are visible continuously and that the audited track record has daily granularity.