I was not trying to change your mind, that's not my job and nor dose it matter. I just wanted to show why we who disagree with you.
Its kinda hard to dispute it when the game which genre you are disputing is classified by the very company that released the game. Anyway goodluck on your quest to become a sega historian.
BOT,Other honorable mentions...
Arabian Fight
Memorable for its use of scaling,has all the key elements that was typical for a Sega side scrolling beat em up,two guys and a girl, its magic melee attacks etc. Unique in western arcades because it was very obvious anime/manga looking which a lot of arcade or other video games that was localized
in for the west at the time weren't (or toned that art style down in some cases.)
DD Crew.
SOR is remembered for being Sega's answer to Capcom's Final Fight, but in fact SOR was actually Sega's second attempt to challenge (or third but i won't mention that game) at the, time the crown of Capcom's ultimate side scrolling beat em up.
The first was DD Crew which was more or less a clone of FF. The sprites while designed to be different to Capcom's game was in style exactly like it, including the sounds from the various fighters. Like FF and SOR the game ends in a final showdown in a corporate high tower with a similar looking villian.
Dynamite Dux
A game that at first glance looks like its going to be a platformer until you play it and quickly becomes an enjoyable romp of punching,kicking and blowing up other cute type enemy sprites. No title like it has been made since and shows why Sega is a unique company for even having an idea to create a game like this.
Spider man the video game
Looking at Sega west's recent Marvel titles you wonder how the hell they fracked up the way they did on those games when they had at one point made some of the best marvel video games. In the early nineties Sega's first deal with marvel became one of the best use of the marvel license with Sega of America's Spider Man vs Kingpin and Xmen 2 Clone wars being the high points. Not to miss out on the fun, Sega Japan did an arcade version of the Spider man license, a 4 player side scrolling beat em up with platform elements. The game's visual style imitating the look of a comic book complete with speech bubbles with villians ranging from Doctor doom to the hobgoblin. Often overlooked but a good example on what Sega japan can do with an american based concept. It was too bad that they weren't involved in doing some of the marvel movie games,who knows what could have been.
Cyborg Justice
Before Ecco, Novatrade came out with this game in which the player constructed or customized their robot which they went on to fight other enemy robots in a series of one on one encounters before you reach the end of the level and fight the boss to get to the next stage. Good idea to combine the side scrolling style of beat em ups to the versus style of beat em ups. Often overlooked sadly.
Comix Zone
Surprised this was never mentioned by anyone let alone included on the list...actually i'm not.
Comix Zone, bar none the best western made Sega beat em up. A game set inside a comic book who then must see the hero fight his way out of it. The use of graphics to portray the comic book style was more effective than what Sega japan did with Spider Man as well as the fact that the game sees you fighting with enemy sprites inside actual comic panels with the main boss drawing in new enemy sprites for you to fight against. Original idea, great use of execution and solid gameplay. One of Sega west IPs that deserve a sequel rather than seeing it get ported or included on numerous collections.