My source is the document the FCC presented as their new net neutrality rules, which can be found here:

https://docs.fcc.gov/public/attachments/DOC-401676A1.pdf

Page 317-318, Section 534-535 "Application to Data Caps"

Section 534 discusses the professor who suggests data caps should be banned, and section 535 discusses how the commission disagrees and how data caps will remain.

535. We agree with Professor Jordan that the Commission can evaluate data caps under the general conduct standard. We do not at this time, however, make any blanket determinations regarding the use of data caps based on the record before us. The record demonstrates that while BIAS providers can implement data caps in ways that harm consumers or the open Internet, particularly when not deployed primarily as a means to manage congestion, data caps can also be deployed as a means to manage congestion or to offer lower-cost broadband services to consumers who use less broadband. As such, we conclude that it is appropriate to proceed incrementally with respect to data caps, and we will evaluate individual data cap practices under the general conduct standard based on the facts of each individual case, and take action as necessary.

Also, you get an upvote for asking for a source. Cheers.