How do these people know that it doesn’t spike their sugars? Are they doing lots of testing? Do they have a Libre or similar device? What was their last HbA1c? Personally I’d take their comments with a very large pinch of salt, decide for yourself what constitutes a healthy diet and then stick to that and forget about what they are saying. Chances are all is not what it seems.
And as others have said, everyone is different, so even if they are telling the truth, what works for one doesn’t always work for another.