The cases of the accordion cracking are reported after instalation of the bracket,I didnt hear of any original EGR to crack there.The EGR is exposed to a substantial thermal and pressure loads.Especially the accordion is on the hot and pressure side of the turbo.The EGR may go thru many heat cycles while driving in city or mixed as the valve may open or close many times,with delay between the openning and closing.Plus there is a bypass channel inside the EGR which also affects the temperature of the EGR.Originally the upper flex joint is designed to take all the flex,but the recall bracket may change the point where the expansion goes.
Your theory looks plausible too.Like most things in life it could be a mix of both factors.

Good thing is that me and the Norway tuner i am working with should be ready to offer some parts of that kind,along with software correction,for EGR and headache free motoring

EGR block-off kit: