You can, and it's actually great if you store little "headers" etc to tell you those offsets. Their design doesn't seem super amenable to it because it appears to be one file, but this is why a system that actually intends to scale would break things up. You then cache these headers and, on cache hit, you know "the thing I want is in that chunk of the file, grab it". Throw in bloom filters and now you have a query engine.

Works great for Parquet.