It can be so tempting. A search for your ancestor on a website turns up with his ancestry back five generations. There it is all compiled and easily downloadable in a file that can be imported into our own database.
In a word, no.
I have located many ancestors in these online files with generations of their ancestry. In some cases, I use this files as clues. Not as facts. If I import someone's information into my file, separating the information out is nearly impossible. Not all submitters are careful about the accuracy of their information.
Just this week I found an online compilation with the ancestors of a first cousin of my great-grandmother. This compilation contained people dying before they had children, parents who with birthdates after their children died, and ancestors who trotted the globe having children in several states and foreign countries. While this example may be extreme, it still makes the point that integrating someone else's data into ours may end in more of a mess than we had in the first place.
And using any website's "automatic" search feature can lead to false positives. I've seen those sites suggest parents for children where dates of birth and death violated laws of biology.