Because I think NIP-01 can be as easy as a collection of shell scripts with GNU and Bitcoin tooling. Designing a proper SDK is a whole different story, but this is not due to the complexity of NIP-01. But it has to do with scaling architecture.
Discussion
For example: my proof-of-concept relay implementation became stuck at the questions:
- why allow multiple filters?
- why not require sorted JSON in the note format (signing issues would be solved without the need for a binary format)