I've found both my reds and my euros to be completely impartial to not just DE, but even things like eggshell powder and oyster flour as well.It sounded like you were saying it didn't harm beneficial insects, but maybe you're just talking about the soil microbes. No it's not gonna hurt my bacteria or fungi. And I know what they say about the worms, but there's actually mixed thoughts on that one.
I'm sure they don't like it at all. But I think they can live through it if you don't overdo it. I know my worms get pissed when certain dry amendments touch them.
It will definitely hurt some beneficial insects.
And as far as beneficial insects, only real risk is in an outdoor veggie garden where you would be hurting pollinators. Indoors, even in my living soil, its completely fine. I'd rather protect against thrips and gnats, as opposed to worrying about the environment for mites that are doing the job that the soil and worms can do anyways (decomposition)