At about the 4 minute mark in that video he explains why.I used to run a trickle into my pond 24/7 in arizona, heavily treated water, it never caused an issue.
If you have a significantly large pond and depend on dechlorinators (water conditioner) for water changes you are either going to spend a fortune of those dechlorinators, or end up not actually doing as many water changes and your should.
Drip water change system is way easier and reliable than doing manual water changes, cheaper in the long run, and safer and healthier for your pond water quality, and no need for any prior chemical water treatments.
However, if you are really paranoid about chlorine in your water and want one more level of insurance you can add a cheap inline carbon filter in the drip line system.