I'm concerned that this will prevent us from writing AssetReaders (and therefore loaders) that truly "stream" the bytes. For example, the http reader used by WASM currently collects bytes into a VecReader, which is why this works. But if we wanted to skip the Vec to avoid the up front allocation of the entire asset bytes, we now literally cannot do that because AssetReader requires seek, which an http request does not support.

Originally posted by @cart in #12547 (comment)