Similar to how Bitcion has BIPs to normalize bitcoin wallets, this is a proposal to normalize the Bitcoin RPC Interface.
Just one example of the problems that arise: If a client doesn't provide getblock or doesn't work in the same way it will have unintended consequences .
Having a standard described interfaces lets you generate documentation, generate RPC clients, test interfaces, across implementations.
Here is the proposal:
https://github.com/bitcoin/bips/pull/776
Here is just an example of what something like that would look like for Bitcoin: https://github.com/bitcoin/bips/pull/776#issuecomment-479649785