It's just using statistical info to make informed decisions. I'm no advocate of market timing or in and out behavior. For the vast majority people are not suited for that behavior. My long portfolio beat the market by > 30%, with basically zero turnover for likely > a year.
The people in these articles are not people to be listening to. Usually if someone's selling their formula, the formula is broken. If I see a decline in the market coming, the last thing I would do is publish it. The most id discuss is ways to make an educated guess (like the sell in May and go away. But that one is bad, 70% probability).
Even if I saw a fall, I wouldnt liquidate. I'd look to raise some extra cash, but there's long positions I'm fine holding through downturns.