My Atari/Sega comment was comparing late 70s Atari and how successful they were on the console and arcade fronts, to how they floundered heavily in the mid and late 80s, all the way into the 90s with the Lynx and Jag. Likewise Sega was up there with Nintendo in the early 90s, and they also dominated the arcades at that time; then they released all their failed Genesis add ons, then the Saturn which flopped, and then the Dreamcast, which was their last stand.
I'm not disputing that Sega didn't have anything good coming out after their Genesis glory day; personally I like the Saturn and Dreamcast more than the Genesis, in fact the Dreamcast is my favorite console of all time. However, their demise was similar, at least in terms of their prominence as hardware devs.