I wouldn't say that the sources are useless necessarily - just the links. They need to be reformatted to be of use to other researchers. This is how I do it. This way other researchers can find the source whether using FamilySearch, Ancestry, or microform since it gives the census information and the roll, district, etc.
Fourteenth Census of the United States, 1920. (NARA microfilm publication T625, 2076 rolls). Records of the Bureau of the Census, Record Group 29. National Archives, Washington, D.C.; database and digital images, "1920 United States Federal Census," Ancestry.com Operations, Inc., 2010 (http://www.ancestry.com : accessed 26 July 2018); Year: 1920; Census Place: Burgetts, Blount, Alabama; Roll: T625_3; Page: 5B; Enumeration District: 166; Image: 819.
So, what I do is put the original source first, then indicate that I found it on Ancestry. You could also put the updated link in the ( ).