By reliable Amazon mean "won't lose your data" and they deliver on that. The issue in the articlew is around latency and Amazon aren't making any claims in that area. High throughput databases need steady latency guarantees so they're not a great fit for EBS. EBS is great for many other scenarios though.
EBS is fine until it isn't. The problem isn't general EBS suckage, it's unpredictable and sporadic suckage. When your DB server is blocking while it tries to write to a disk that isn't responding, things get really hairy really quickly.