> Kind of a shame someone has to specifically implement a low memory usage library. That implies other implementations went the lazy route.

Streaming and seeking are antithetical, an implementation gets to pick one, and I imagine for most users streaming would be the edge case. It's debatable whether a library that ensures a fully spec-conforming output is generated at the expense of memory or IO is better or worse.

(FWIW this is written from the perspective of someone who for perverse reasons once wrote a streaming ZIP reader. In order to build such a thing, the ZIP writer had to be buffering/seeking. You can't have both without giving up ability to store uncompressed assets without needless overhead (e.g. JPEG-in-deflate))