...are actually not a good idea, at least according to this article:

And here I will repeat, a Kobe burger is always, always a bad idea. When cooked rare to medium-rare, as most chefs who put these on their menus usually recommend, the texture inevitably renders as mushy. It's like moist cat food on a bun, with the meat oozing out the sides and back as you try to eat the burger. Why turn a glorious piece of beef into minced meat?

Kobe burgers are most often seen in mini-hamburger form, usually as an "appetizer" plate of three burgers, because A) this expensive beef is more affordable in smaller, sharable portions and B) the Kobe/Wagyu and the min-burger/"slider" trends seem to have peaked at the same time. Thankfully, both manias seem to have abated and you don't hear as much about these ill-conceived lil' ditties anymore.