I'm more concerned about the opposite effect -- that the default subreddits have become pointless and boring, focusing mostly on "funny" images and cat gifs. Gone are the interesting askreddit threads or useful world news commentary, replaced with content designed to keep you browsing and staying on the site longer.
At the same time, I think the useful content often falls victim to Gell-Mann amnesia, giving votes to anyone who sounds like an expert. It's hard to identify when someone is really an expert or whether they're merely writing like one... The worst I saw was an explanation of laminar and turbulent flow that was 100% wrong, but highly upvoted until a few hours later people pointed out why it was wrong