@carterfox Because MERs in mutual funds includes the cost of advice. There are two debates here: active vs passive management, and advice vs no advice.
A mutual funds that track an index is really a passive investment, so paying a high MER if you aren't receiving advice makes no sense - some people are simply by the wrong series of the fund. Similarly there are ETFs that have an active strategy. Active vs passive is its own investment debate.
Advice vs no advice is different. Generally (I use generally cautiously, this subreddit is biased towards people who believe in DIY) people who get independent advice make better financial decisions, beyond what investment products they choose. There are good and bad advisors out there. Challenge with MERs on mutual funds is that there isn't full transparency what the cost of the advice is since it's baked into the cost of the fund, so people don't understand exactly what they're paying for.