I consider it one of the main reasons Apple lost so much content market share to Amazon despite Apples first mover advantage - Amazon has better search and you can actually find the stuff you want. AFAIK Apple tried to start up an applied research group to fix the problem but they refused to pay enough and ended up with the dregs. They tried to hire me 3 years ago for $130K. It highlighted that they didn't understand the importance of the problem and we're likely to fail. I typically make ~$240 as FTE and more as a contractor. Apple also has a culture of secrecy where as search science is pretty open.
Anyway; I checked out Steam. The search there is clearly very poor and can easily be improved. The overreliance on tags is usually a good indication that they are not digging into their usage data for their recommendations.