> The crux of the problem is that it is not entirely clera what the correct smallest size is. Indeed that optimal size may vary for different deployments. If you make the buffers too small, your router will under-perform - especially in benchmarks in high-bandwidth settings. Making them too large OTOH is unlikely to cost you sales: few people benchmark performance in real-world scenarios, with congestion - except network congestion researchers.
Agreed that the exact *optimal* size is not clear. However this is not an excuse for unreasonable sizes that harm latency with NO throughput benefit.