[switchbak]

I don't care that much about performance - I imagine any modern machine can handle that load pretty well, for this context that's not a huge concern.

The concerns are more about distributed systems issues, maintenance, etc. Typical NIH issues. Which you're embracing when you start building your own systems (ie: with sharding).

This is a solved problem, why would I want to inject these burdens onto myself, instead of solving ... actual problems that I already have enough of! I don't want to be building another Temporal/Cadence/DBOS/etc.