DNS does not tell the whole lifecycle story, but it is an excellent early warning system.
If a domain has live nameservers or starts resolving again after being listed as a drop, it may have been renewed or registered again. If it returns NXDOMAIN at the registry layer, it may be in redemption, pending delete, or released. RDAP is still needed for authoritative status, but DNS helps decide what deserves RDAP first.
NameNotifier uses DNS as a filter and RDAP as the stronger truth source. That keeps verification focused on domains where the evidence changed.