It's impossible to draw this conclusion when Xbox is just not putting out games at all. If Xbox 1st party heavy hitters were consistently selling gangbusters on PC, while Xbox hardware and software languishes, you'd have a story. Xbox hasn't had heavy hitters for a long time.
Did it hurt the PS4 that many 3rd party "exclusives" were day and date on PC? I'm talking about No Man's Sky, Street Fighter V, Nioh 2, Nier Automata as examples. Did millions of people abandon the platform in favor of their computers?