If you believe the market is 100% efficient, then it follows it always has been this way. Do you really think the market is equally efficient as it was a 100 years ago? If not, then it follows that market efficiency is a gradient, and gets more efficient over time. I do not believe the market will ever hit 100% perfect efficiency. There is room for improvement and room for longer term alpha.

Another argument against EMH is to assume it is true. Market wages for quants and hedge fund employees would reflect their true value. But wages for quants are a lot higher than the cost of using a random number generator. If all trading success can be attributed to luck or chance, it would make no economic sense to hire expensive quants, hence EMH being true leads to a contradiction.

I do believe in a no free lunch theorem for market pricing. Averaged over all traders and all stocks and all strategies, there is no perfect approach that beats the market consistently. But that is of little practical value (in inference and search the no free lunch holds, but we can still use prior information to limit search ranges, focus on the profitable markets, and use approaches that worked on similar problems).