They might have gone completely by the wayside in 2017 or the generation overall, but boss battles use to be a much bigger staple of video games. Topping off any given level or giving you one last reason to roll together all your accumulated skills into one show-stopping finale before the credits, there's immense merit to designing damn fine boss encounters.
However, the very reason they're rarely included in video games today, is the sheer challenge involved. Sans for some optional endgame encounters, even Super Mario Odyssey sticks to its tried and true "hit them three times and you're done" formulae across its entirety, forcing diehard gamers to look elsewhere if they really want a challenge.
Say what you will about Dark Souls making balls-hard challenge its main selling point too, FromSoftware's runaway success is pretty much the only major franchise this decade that effectively do something new with how bosses are designed and defeated.
Indeed, when a good fight is so hard to perfect, it means there are tons that end up being genuinely infuriating, leaving your options as either give up forever, or fight until you're a quivering wreck.