Obviously if you do not hold significant cash and are going to invest your savings monthly there is no difference between DCA and lump sum investing.
However, what retail investors should be doing is investing some fraction of their paycheck each pay cycle, or something like that. That's not the same thing. There is no lump sum at their disposal to invest - they're investing as soon as they have the money. What they're not doing is saving up cash and trying to buy the dips in lump sums, which I think most would agree is a bad idea.
So they're both investing as soon as they have the money available, and they're benefiting from the averaging, which you may or may not call 'dollar cost averaging'. It seems ideal to me, and this is what I think the comment you're replying to is referring to.
Those things shouldn't change in response to short-term market fluctuations, but not all external events are limited to short-term market fluctuations.
The key is to maintain a mix that allows for short to medium term fluctuations in the market (and economy) like this.
EDIT: I highly recommend the book "A Random Walk Down Wall Street" for more details on asset allocation strategies at various ages.
Why are stocks a valid strategy (where there's possibility of easily losing 20-30%), while losing a few percent due to inflation in something like a savings account isn't?
also see cFIREsim for an idea of the math: you're basically guaranteed to run out of money if you try to park in safe havens and you end up living a fair bit after you retire.
If you are struggling to stay within a "safe" withdrawal rate of 2-3%, you may find that equities are your only chance of getting the returns that you need.
Ex. If you're 40 and think you'll live to 100, try to hold 40% bonds and 60% stocks.