With how low fees have gotten, I think the more likely and more damaging situation is that where people's employers have negotiated much worse pricing for their captive audience. I wouldn't give 0.08% vs 0.037% a second thought any day. That's only difference of $400/yr on $1M!
Compound it over 30+ years and even those few bps add up to a significant amount.
The real mover for lower retirement plan fees was lawsuits. There have been loads of 401k excessive fee class action lawsuits and this got almost every employer negotiating to avoid this. Of course there's some plausible deniability in some cases but there is something on the other side against that https://hallbenefitslaw.com/401k-excessive-fee-class-action-...