computer filesystems have been refined for structuring the data to optimize seek latency for over 50 years. there really is no place you can look in the field for a better option for finding and retrieving large amounts of data quickly.
back in the olden days, i sometimes was running my linux installation on ReiserFS, before he got put in jail for killing someone (lol, i still can't comprehend that). reiserfs was one of the most notable filesystems in the field of data storage for pionering optimizations for the big and little problem in filesystems. ext4 has a substantial amount of them and iirc, reiser was the first to have a two stage commit journal that wrote constantly append only log and a worker in the background that compacted them into the filesystem when idle, populating the necessary metadata tables.
while there may be other variants of data structure storage for fast searching indexes than LSM K/V stores, as far as i know, for general usage it's still the best strategy and is very friendly to kernel disk cache memory.
the more the iterator has to decide as it progresses about where it's reading from next, the less time it's doing the reading of the thing you want. that's why it matters, and that's why there's no sane reason to reinvent the wheel for large blob storage. very few production systems have implemented it any other way.
