I don't known, but to me it seems as the if the author of the article doesn't have his own stuff together. If one cannot sleep during nights, then it's due to excessive position sizing or due "control issues" or stuff like that. I think those issues with swing trades will also manifest in intraday trading, but in different forms.
One way to assess the effectiveness of day trading strategies is by how much of the available “daily travel range” a strategy is able to capture each day in combination with reasonable R/R (other variables need to be removed). Unfortunately, most index scalping / intraday trading strategies fail miserably in this regard. Obviously, there are exceptions, but those are rather rare.
The way I see things is that the definition of day trading is being flat overnight. It has nothing to do with trade frequency. No one needs to be married to a monitor and react to every price wiggle and riding the emotional roller coaster while formulating their trading plan in the heat of the moment.
Many index traders keep on spinning the wheels because the indices don’t present that many quality setups as a universe of big cap stocks does, therefore most index traders take sub-optimal trades on very low TFs (in attempt to increase opportunities), and it often becomes a never-ending struggle for some of them.
However, if an intraday trader trades a universe of big cap stock, he then can choose explosive setups that capture ¾ of the available daily range (if one is good at identifying stocks that are being bought/sold by institutions). That's one way to create a "leverage".
At the end of the day if there is still institutional buying/selling pressure in that stock, then the profit can be used to buy an option and turn it into a swing trade (with defined risk). With trades like this, the R/R can be very high, providing the initial risk was defined on a M5 TF in the morning.
The above is just one method of many on how to swing trade with very limited risk in stocks that are being chased / sold by institutions. They’re big elephants, they cannot hide.
Intraday trading can be used to fine tune entries and to limit risk, and not as the only way to trade full time. There are many ways to trade the market.