I have no idea why you think that all attributes need to be buffered in process forever. Most metrics systems simply keep key sets in ram cached for as long as

I have no idea why you think that all attributes need to be buffered in process forever. Most metrics systems simply keep key sets in ram cached for as long as they're still being emitted. Many drop unused key sets after like 10 minutes. But like all metrics processing, you should ideally keep cardinality to a bound set in order to avoid these types of issues both client and server side. I'm sure there are valid qualms with OTEL in general, but this ain't one of them. Any and all metrics telemetry systems can fall into the same design constraint you pointed out.