I believe that's what the parent meant. At any given moment your money is somewhere: stocks, cash, bonds. You transfer from one to the other when you feel the time is right for it. In that sense every move is market timing.
That does imply that most people shouldn't move their money very often. Do some research, buy and hold, and don't worry overmuch about whether you bought near the top or the bottom. Put new money (e.g. salary) into something with low overhead, like an index fund, unless you've got good reason to think you can do better with a specific choice of stock.
If you find a bargain, buy it. But buying bargains is a matter of timing: it's only a bargain if it goes up eventually.
Most people sell labor or knowledge for 20-50 years during their lives. Pretty much continuously. So during a recession you can spend some of the money you get from your labor on stocks that are "on sale".
That's a lot of ifs, but that's precisely what we're discussing - how best to behave in different circumstances. "Always hold" isn't the best answer in all circumstances, despite what many in this thread are saying.
1) Your goal in investing
2) Heuristics to achieve that goal
The goal is to maximize your investments over a time, as I stated. Yes, you're absolutely right that holding is a phenomenal heuristic. But that doesn't mean it's always the correct thing to do.