Haha the rest of the team might have some more insight here as well…
For some backstory when we first started building Daft we considered using Polars, Datafusion or Velox as an engine
Unfortunately we had various use-cases that were hard to fit into these frameworks. For example we allow for Python object columns (mostly as a escape hatch for arbitrary user-provided Python objects) which are hard to fit into other purpose-built frameworks
And we also wanted to innovate heavily on types, I/O and functionality (building in tensor types, image types, eventually types for documents and video as well) which felt like it would be really difficult to extend in a 3rd party engine 😞