Well, I actually ran into the "Matt Mercer" effect from new players back when I was running Adventure League games. So I mean, it is real, but comments like "it's a plague upon the hobby" are definitely hyperbolic. Sure, maybe your expectations were dashed when you found out that most D&D games involve a lot more combat and die rolling than players acting in character in a professional manner, as well as a whole lot more table talk and jibber-jabber, as well as a whole host of distractions. And most D&D games don't have professional voice actors describing the scene in a manner that has players hanging onto every word, and quickly visualizing what's going on.
But when you get right down to it, it's better that way. Playing D&D with friends is a social experience. Meeting and talking about what's going on, the game being sidetracked by tangential discussions, taking breaks for food or (if you have smokers at your table) a cigarette are just a part of the experience, the kind of thing that gets edited out in a show like CR. Because at the end of the day, Critical Role is a job. It might be a fantastic job, and a lot of fun, but there's a lot of work involved as well, and that's a key difference, I think. I once had the experience of being paid to DM, and as good as the money was to have, never again. Turning one's hobby into one's job comes with a whole host of new worries and eventually your brain will rebel about it sucking up so much of your time.