This doesn’t seem correct to me.
Products would still be searchable, but the wealthiest companies could no longer pay for placement or pay to have their brand name repeated endlessly so it’s on the tip of your tongue but you don’t know why.
People would still talk in their communities and share recommendations.
Reviews (unpaid) would still be a thing.
Markets (real and virtual) where you can compare competing products and make a decision wouldn’t go away.
Reddit also grew more rapidly in recent years post-IPO for similar reasons. Reddit used to be more niche with fewer people even knowing it existed.
Knowing alternatives exist is half the battle. This fair comparison you hope people will make is just a hope without the ability to advertise. People have to know all possible alternatives exist in order for the market to be perfectly competitive.