I don't think earnings is an antiquated metric for valuing companies though. Other metrics exist to estimate future earnings and attract a different class of investor looking for different risk/return profiles than people wanting to index companies big enough to generate steady returns with fairly high confidence they'll be doing a similar thing tomorrow. If people want to invest in a different type of company from the companies the index was designed to capture they're entitled to do so: if their expected returns are that good you don't need to browbeat indices into changing their entire ethos to get funds involved in their IPO.

Sure, some companies which vastly outspent competitors on growth became very successful profitable midcaps and joined the relevant indices when they did, but everyone else waited their turn (including the ones that never became profitable midcaps because the money tap was their moat)