Well, top 20 micro is a little bit different than top 400, not everyone is top 20 and things dak deals at below that exclusive top level are a little bit different.
That's true, however the variety of viable strats at the highest level is extra sparse usually. And if Flakvierling is not 100% mandatory at top level, I just can't see why it would suddenly be mandatory at the lower levels where your opponent makes more mistakes too