This is an issue that comes up quite a bit and yet there’s still no great answer from either side. People will make claims without backing them up or they’ll link you to unbearably long forum posts with scarce sourcing.
As you pointed out, the Privacy Guides team believes there’s no point in worrying about it. Elsewhere on the internet, some will say it’s a bad idea to disable IME and others will say it’s good. It’s not a great answer and I’m hoping the Privacy Guides team can eventually write an article to finally address this long unanswered question.