EIPTools offers an alternative page that hosts all the EIPs, ERCs, CAIPs and RIPs, removing the single point of failure if the ethereum.org website was to go down.
It is a crucial piece of infrastructure as the EIP authors can propose new EIPs and share it's EIPTools links with their community that can read the EIP in a human accessible format (instead of navigating through GitHub PRs). This allows further discussion within the community before the EIP gets finalized.
A major example is of the ERC-7710, the official Metamask website links to EIPTools to share info about this ERC.