The useful question is not how important a tool feels but what would be irretrievable if it vanished overnight. Three classes behave completely differently.
A dead interface is recoverable. When a tool is a view over state that lives on-chain, its death costs convenience and nothing else: the proposals, votes and balances are still there, and anyone can read the contract or build another front end. Tally's 2026 wind-down is the worked example, and the reason it was survivable is precisely that the Governor contracts it fronted never stopped working.
Aragon's own relaunch shows the same boundary inside one vendor. On 30 June 2025 the current Aragon app replaced every earlier version, and existing DAOs had nothing to do, because their proposals and settings live in OSx contracts. The developer layer fared differently: Aragon deprecated its legacy SDK and subgraph for OSx 1.3 and earlier and said it would not update either for version 1.4 or later, so an integration built on them cannot follow its DAO past 1.3 (Aragon).
A dead hosted record is lossy, and the loss is the reasoning. Workspaces, forums, and payment apps hold the material that never had an on-chain shadow: the draft that became a proposal, the objection that changed it, who held which role in which month, what an invoice was for. When CharmVerse's application host stopped resolving, that class of material went with it. A DAO in this position keeps its money and its contracts and loses its memory, which is the half that made the money legible. The same boundary shows up even in healthy tools: Den adds no contracts to Safe, so the human-readable description a signer reads sits on Den's servers next to a payload that is immutable on-chain.
A live contract with a dead maintainer is the dangerous one. Deployed contracts do not shut down. An unmaintained module that still holds a role on a treasury Safe, a badge contract that still gates membership, a streaming contract that still holds a balance: all of these keep executing exactly as deployed, which is the problem. Nobody ships the fix, nobody answers the disclosure email, and the standing permission outlives the company that asked for it. A dead front end is an inconvenience. A live privileged contract with nobody behind it is an open item on the attack surface.