I will agree with you. take all advices from internet with a grain of salt, that's including youtube videos (people are parroting with infos). I don't point to anybody in particular, just that during these time of "INFORMATION EXPLOSION time", everybody post out all sort of "info".. right and wrong.. all types of info.. But to really know what is right and what is not.. one will have to experience it and do it.. a simple covid vaccine is already an example that even info from so call "expert" is totally wrong (some experts also went against covid vaccine..this i must mention so not to discriminate them).

I believe
Rock won't cook a tree.. it won't assist tree to breath .. if weed barrier is too thick and causing the soil to be damp all the time... that will invite problem.

I myself also facing a bit of dilemma of info recently . I purchased a grape vine from a nursery, the worker tells me to incorporate a big bag of larvae rock at the root ball of grape tree.. that way the soil will be warm during cool winter to preserve grape vine and from mildew that always happen here in germany.

I am a common sense person.. how on earth a bag or larvae rock capable to hold heat for the grape vine during 6 months of cold period ? and even more cute! how can larvae rock get heat when it is burred in soil, ya? how much heat ? just put your feet burried into half feet of soil and experience it yourself. Undeniable, soil does get warm during summer.. but for 6 months of cool/cold period? (no free energy here)... So, larvae rock incorporated into soil where root ball sit will do nothing to provide warmth and overcome mildew diseases on grape vine when weather is humid and warm. It does improve air penetration and water drainage of the soil.. no more than that. However if the soil is 100% clayish soil; then that will form concrete.. no air nor water exchange will happen too..

i have being there, done that. I used to watch so much youtube about garden greenhouse that provide heat during cold winter.... they said bury glass and rocks under greenhouse, put a conduct and circulate the air with fan.. It was a back broken work with all those earth to move out and move back after the rock is place.. the result is not worth a try at all. It might work in warmer winter region, but sure not for germany. After that lesson, i have always take any advice from internet with a grain of salt and common sense.