I would argue they're more mechanistic than diversified
They are one strategy. There could be many others, just not in a 401k. I want a basket of strategies, not just a basket of prominent names.
I want to know if 35% of every index fund is invested in the MAG 7 or the same 30 global tech names.
Who are the managers, what is their track record? Is it basically a closet index fund? "We select undervalued stocks with growth potential for capital gains." Oh, really? Is that a strategy?
I'm finding funds with vague objectives managed by multiple fund advisory companies who have no real claim to fame. Average is being hitched to growth in the overall economy. I want a discernible path to returns that beat the market averages.
Advisory fees are leeching investors every bit as much as insurance agents are doing to Medicare. IMHO