In a healthy system impact is negligible. The issue is for people with VM/MAV there is an impact and I believe it's the Potassium content. Both of these contain high levels of Potassium (if you substitute 'coffee' for 'caffeine'). If you look at every one of the '6C's' they are high potassium items. Additional ones are bananas and avocados.
Restricting these things may improve symptoms but it's never been proven in controlled tests afaik.
However I can certainly atest to experiencing much worse tinnitus after having had a salty meal that included cheesecake and red wine. Perfect storm.
Coffee is a funny one though. It's also a diuretic. So the question remains does your potassium level go up or down after a black coffee?! Best not to have a latte I suspect as the milk contains yet more Potassium ...
Also you definitely need minerals to be healthy. I guess the goal is not having massive peaks of these things hence the restriction is only of items that have particularly high concentrations.
Found this interesting link about drinking Green tea wrt Potassium levels: