I think it's also worth noting in these conversations that play-by-play announcers typically have a much bigger impact over the quality/listenability of a broadcast than a color commentator. So while Edzo has his annoying aspects, I would argue that it's much easier to tune him out and simply not have him affect the viewer's experience too much. (There are exceptions to this, most notably Pierre, I suppose, who talked a lot and was so over-the-top in some ways that it was hard to ignore.)
With a play-by-play announcer, viewers are almost forced to pay closer attention because we want to know what's happening and who's doing it. And in a way, national broadcasts are even more crucial for this than local ones because many viewers can't identify or don't know players from both teams.
So even getting beyond issues like the timbre of Hextall's voice and things of that nature, her #1 job is to be able to identify the action and the players as seamlessly and naturally as possible, and she's simply not been good at doing that.
Between her frequent misidentifications, confusion about what's happened, and dead air, Hextall does something that I want to relate to the novelist/writing instructor John Gardner's lesson from his book The Art of Fiction about "the fictive dream": she pulls us out of our focus on a game, which we're immersed in and watching intently. As Gardner says of the writer, which could be said for the play-by-play announcer (who effectively functions as a game's narrator), "By detail the writer achieves vividness; to make the scene continuous, he takes pains to avoid anything that might distract the reader from the image."
I tend to watch a lot of hockey (I probably should spend more time reading and writing!), and while I like more announcers more than others, there are only a handful who tend to pull me out of a game through the way they're calling it, if I'm actually immersed in the experience (which is less frequent these days, with all the distractions at hand). Hextall unfortunately is by far the worst at this, alongside Jack Edwards (who used to actually call a pretty good game, but no longer even does that), and it's a shame that ESPN put her in this position before she was even close to ready for it, inviting all this criticism (which really should be primarily directed at the network).