I mostly agree, but I think you're too quick to assume that everyone who doesn't write optimal code is doing so because of some tech fad. Frequently it simply doesn't pay to write optimal code; there's no viable business case. Sure, using an array can be faster and not much harder than using a hash table, but writing a network protocol is frequently not worth the effort. In my experience, poor performance comes from the inability to make a business case (whether or not one actually exists), not from chasing fads.