I can't even have a delicious decaf-coffee, because of how oversensitive I am to the damage that caffeine does.
( "decaf" coffee usually has about 4% of its caffeine left, ttbomk, it absolutely isn't 0% )
As for why on earth it'd do any damage/harm, caffeine blocks-access to subtler meditations/inner-yogas.
It's like not being able to breath: it blocks the whole category, and you never even know the category exists, until you earn access to it, through sattvic diet.
Forced to choose between delicious decaf coffee vs the meditations that are saving my health & life, .. sorry coffee, bye!