ollama is a thin wrapper over llama.cpp, so i'd pose the opposite question - what does ollama give you over using llama.cpp directly?

Model management, customisable HTTP APIs, monitoring, security features, "parallel requests" (batch processing), no requirement for HF auth etc...

Ease of use. Rather like arduino or like docker vs chroot/jails/zones, there's nothing wrong with just using the underlying tech, but lowering friction has value.

and I tried both of them and ollama some how handled everything better for gemma2