I only watch Tettles occasionally, and he is definitely not happy about the power coming with covenants as far as I know. He has voiced his opinion on that.
Also, Preach has a lot more videos praising Shadowlands than he has complaining. The reason his covenant related videos are so popular is because it’s a controversial topic and considered a problem by a lot of player. Plus he’s one of the largest active WoW content creators, so his videos on this are naturally getting the most traction. I don’t think he’s doing any of this for attention. It’s literally his job.