Tatsuki Fujimoto has managed to create a modern masterpiece work filled with creativity, iconic designs, well-executed story progression, amazing fights, hilarious humor, an intriguing atmosphere, a vast cast of well-developed and likable characters, breathtaking devil designs, subversive and unpredictable events, high tension because characters can die at any moment, an adult tone due to mature elements such as nudity, sex and gore, well written females that are on par with their male counterparts(a rarity among shounen), a modern feel that fits the current zeitgeist of our society, a clear starting and ending point, a perfect story length that ensures to keep the interest of the reader, unique concepts that have not been used in a long time, a perfect balance between action, humor, and catharsis, foreshadowing of important moments thanks to competent writing, arcs that seamlessly flow into each other like a river, and most importantly: it manages to stay entertaining from the first to the last chapter, something that only the 1% of fiction can achieve.
Chainsaw Man ranks at the very top of the manga hierarchy and does what it tries to do with incredible proficiency, it's a modern marvel of creative storytelling. However, /a/ seemingly ignores all of those points, and only attacks CSM for its small number of mistakes, while simultaneously not acknowledging its positives. They only do this because of the deserved industry-wide recognition it received, and not due to its actual minuscule amount of flaws. This obviously leaves the fan base with frustration, and in an attempt to retaliate, they're vocally voicing their opinions on why Chainsaw Man is actually an amazing work. This can make them seem “annoying” when it's in reality just their inevitable counteraction to /a/'s ignorance and biased criticism.
Chainsaw Man fans aren't annoying, it is /a/ that is at fault.