*WHOOSH*
OK, let me see if I can explain (ruin) the joke:
The promotion of ATR with 1 day interval as the way to compute ADR is biased by the fact that the resulting indicator isn't as smooth and therefore tends to generate more trade events, which means you pay more commissions than someone using simple moving average to compute ADR. Cui Bono? The exchanges charging the commissions -- who are likely behind the promotion of ATR with 1 day interval as "superior" to SMA ADR.
"But its so average..."
I guess 'average' is a play on words (double entendre) of some kind perhaps the "its" referring to "it's" as in the 1day ATR being no better than SMA ADR in predicting trade opportunities, so, in order to avoid the added commissions, "keep looking for an SMA ADR"? Or did that phrase also go *WHOOSH* over my head?