For an extremely specific and rigid use case / workflow, sure it's a close alternative.

For most people that want a flexible, extensible product that can do many things in many ways, it's probably not nearly as close an alternative.

It’s an alternative for the “do not touch any plugin” crowd, which I would assume is the majority of Obsidian users. It’s not a replacement for the “install all the plugins” long tail, sure.

For my use I considered both and honestly Zettlr is not that far behind. Decent Zotero interoperability would have sold it for me.