I've tried everything from Nextcloud, ownCloud, OpenCloud, and Pydio Cells. But I still can't seem to find exactly what I'm looking for, and I'm wondering why it doesn't already exist. File storage is (in my opinion) one of the most helpful use cases for a self-hosting setup, but I don't understand why there isn't a self hosted cloud storage platform that:

• is cross-platform
• has relatively low resource usage
• uses a flat file structure, not S3-style blobs
• handles thumbnailing for more file types than just images
• has virtual filesystems OR selective sync for common operating systems
• has decent sharing or multi-user tools
• has good upload and download speeds

Essentially, I don't understand why a fully self-hostable and user-friendly Google Drive alternative doesn't exist. I'm a developer and I understand that it would obviously be a large undertaking to build, but it's a type of software that's very common for self-hosters and I don't see why a better option doesn't exist than the established players. NextCloud is too heavy/is trying to do too much, ownCloud is too corporate and a pain to maintain (plus the interface is crap), Pydio is good but the client apps (aside from the web app) are horrendous, Seafile is limited to blobs and is slightly proprietary, FileRun is paid, etc. Just seems to me like a major gap in the space. Anyone have any insight on why something like this doesn't exist?