Growing dragonfruit from seeds gives you a huge number of dragonfruit cactus plants in a very short order from the large quantity of dragonfruit seedlings and is very efficient in preparing a high quantity of new dragonfruit cactus plants in a very short time. However, sometimes dragonfruit cactus propagated from dragonfruit seeds take a longer time to grow to fruiting than dragonfruit grown from stem cuttings even though dragon fruit cactus is a quickly growing fruit plant and the dragon fruit growing conditions meet the requirements of climate that the dragonfruit plant can grow in successfully.
For these and other reasons, if you have access to buy or 'borrow' dragon fruit cactus stem cuttings from healthy and robust mature (at least 1 year old or older and already proven to product dragon fruit in quantity and of good quality) - by all means that is a great way to propagate dragon fruit cactus plants. If you need a very high quantity, nothing beats starting from seeds for sheer rapid quantity production of seedlings, but if you are replacing a single dragon fruit cactus plant or even several, you can get a good head start and an assurance of quality if you start with a dragon fruit cactus stem cutting of a robust and exceptionally healthy dragon fruit cactus (likely a mature dragon fruit cactus you already manage).