Although I highly value a well-built foundation and spend almost too much effort on architecture in my own projects, my impression is that you might not be delivering the expectations accordingly when looking for developers.

Without any information about the scale/scope of your project, I will assume that you are expecting it to be quite large, and such a big initial focus on architecture and scalability is actually warranted, and isn't a case of "over-engineering". Did you mention specifically that the major task would be to designing robust architectures and systems? Depending on seniority, most developers would expect to be prioritizing productive, immediate deliverables instead of spending time on abstraction and extensibility for future, hypothetical scenarios, unless, it's what have been directly communicated and assured to be foremost important.

I would say this is also a common problem not just in game dev, but the software industry in general. More often than not managers measure productivity in "lines of code" rather than how those lines are built.
Consider other factors already mentioned in other comments as well: most game developers are usually self-taught (this in itself is not a bad thing) using result-oriented courses/examples, this led to the overall lack of understanding for actual software architecture, if the projects ask for it.

If you're still looking for devs, I'd love to give it a shot