A benefit would be that in a thick registry one could develop a secure method for a gaining registrar to gain access to the registrant contact information. Currently there is no standard means for the secure exchange of registrant details in a thin registry. In this scenario, disputes between the registrant and admin contact could be reduced, as the registrant would become the ultimate approver of a transfer.
Centralized databases operated under a single administrator that sets conventions and standards for submission and display, archival/restoration and security have proven easier to manage. By contrast, a thin Whois model is a decentralized repository6. Registrars set their own conventions and standards for submission and display, archival/restoration and security registrant information. Today, for example, Whois data submission and display conventions vary among registrars. The thin model is thus criticized for introducing variability among Whois services, which can be problematic for legitimate forms of automation.
A thick Whois model offers attractive archival and restoration properties. If a registrar were to go out of business or experience long-term technical failures rendering them unable to provide service, registries maintaining thick Whois have all the registrant information at hand and could transfer the registrations to a different (or temporary) registrar so that registrants could continue to manage their domain names.
A thick Whois model also reduces the degree of variability in display formats.
a thick registry is better positioned to take measures to analyze and improve data quality since it has all the data at hand.
the extensible provisioning protocol (EPP) was not designed to handle the extensive updates every time a registrar makes changes to the Whois record.
Proponents of requiring thick Whois argue that being able to access the thick data at both the registry and the registrar level will ensure greater accessibility of the data. The draft report of the Implementation Recommendations Team put together by ICANN's Intellectual Property Constituency stated "the IRT believes that the provision of WHOIS information at the registry level under the Thick WHOIS model is essential to the cost-effective protection of consumers and intellectual property owners."
There are at least two scenarios in which the additional option of retrieving the data at the registry would be valuable:
1. Where the registrar Whois service might be experiencing a short- or long-term outage (in violation of the registrar's accreditation agreement), and
2. Where the registrar has implemented strong (or sometimes overly-defensive) measures to prevent large-scale automated harvesting of registrar data.
Also, in the event of a registrar business or technical failure, it could be beneficial to ICANN and registrants to have the full set of domain registration contact data stored by four organizations (the registry, the registry's escrow agent, the registrar, and the registrar's escrow agent) instead of just two organizations (the registrar and the registrar's escrow agent).