David,
I share your view that one needs to be careful about managing expectations for tax loss harvesting, especially and agree the benefits can be overstated. But for long term investors in low tracking error portfolios the potential to defer taxes over long periods is huge, and the probability of doing so is high. With the stepped up basis provisions in the 2017 tax bill the benefits can be greater still. I encourage you to read the article I co-authored in the Journal of Wealth Management, Fall 2016, titled "Pick Your Battles: The Intersection of Investment Strategy, Tax and Compounding Returns." Hope it is useful.