My guess is that this is less harmful than messaging seeking to make people nervous about fruit and whole grains, which are great for BP and lipids (generally at least as important as BG) and which, despite the Internet, do not cause eg insulin resistance or T2D.
Maybe it's necessary to limit portion sizes while getting a handle on a new T2D DX, if you get a big & long-lasting BG rise from individual examples of grains and fruit, and that should certainly be part of the messaging.
But that should go along with the message that it may well be that you won't need to restrict them forever, which is great, because in general they are super-healthy.
EDIT: Nutrition scientist Mario Kratz had a nice blog post & video yesterday, walking through the studies looking for a signal of increased insulin resistance due to carb consumption, and not finding it.
A common claim on social media and in several nutrition books is that eating a high-carb diet causes insulin resistance. In this blog post, we review whether this claim is supported by scientific evidence.
nourishedbyscience.com
I guess increased insulin resistance => new or worsening T2D, obesity etc etc etc is the main claim for why all carbs are evil, apart from transient BG increases. It has been refuted over & over but it's one of those beliefs which seem pretty much evidence-proof, unfortunately.