Here are some quotes from the articles I linked:
"A straddle consists of buying or selling both a call and a put of the same strike. Usually this is done with
at-the-money options and therefor is initially a
delta neutral strategy as at-the-money calls and puts have around 50 deltas"
"When you trade a long straddle, you think the stock is going to move away, either higher or lower, from its current price. For this reason, long straddles are
typically placed on at-the-money strikes."
So yes, by default, straddle is initiated at ATM strikes. If using OTM strikes, it is usually specifically mentioned because it changes the goal of the trade from non directional to directional.
If you look at my article
How We Trade Straddle Option Strategy, I explain:
"I would like to start the trade as delta neutral as possible. That usually happens when the stock trades close to the strike. If the stock starts to move from the strike, I will usually roll the trade to stay delta neutral. Rolling simply helps us to stay delta neutral. In case you did not roll and the stock continues moving in the same direction, you can actually have higher gains. But if the stock reverses, you will be in better position if you rolled."
The concept of straddle being non directional by default is so basic that I really don't want to waste any more of my time on it. Twisting my words and misquoting me won't change those most basic facts.
But I guess this is the level of knowledge you get on a free forum like ET. As they say, "you get what you pay for".