And lets face it...sonic 1 vs mario 1 at the time, sonic was better looking and appealing with more varied levels and music plus graphics. So i get why people into mario at that age would hate sonic.
The comparison was Sonic1 vs. SMW as that was the SNES pack-in title and what Sega chose to showcase in the famous TV ads in 1991. Sonic1 was a fine platformer and a great brand mascot, but even by the time Sonic2 arrived SMW was old news so no one was framing the Sega vs. Nintendo debate in those terms. The culture by 1992 was preoccupied with Street Fighter 2 on the SNES, while Sega was beginning to align their brand with sports franchises. The big story of 1993 was the MK1 ports.
The Sonic vs. Mario thing was, at best, a ~6 month microcosm of the "console wars" in the months following the SNES NA launch. The "hate" was, and is, overstated. Chalk it up to games media personalities giving exaggerated hot-takes for effect. Sonic wasn't and isn't relevant enough to feel that strongly about.