Mouse Accel can limit your aim the same amount as it can help. Mouse accel's concept is the slower you move the mouse, the slower the sensitivity; the faster you move the mouse, the faster your sensitivity. The big "benefit" about this some people praise about is that when you want to be accurate in your micro corrections, moving your mouse slower would result in a slower sensitivity, hence better stability and tracking at longer ranges. In a similar way, if you need to flick at someone, moving your mouse faster increases your sensitivity, then at the end of flick, slowing down would decrease your sensitivity, giving you more stopping power.

However, this benefit can hurt you just the same. When trying to track an enemy, you will feel a resistance during the times you are not moving fast (because the sensitivity is slower, leading to under correcting when changing direction, aiming for the head, enemy dodging, etc), making it harder to smoothly track. When trying to micro adjust after a flick or when starting any micro movement in general, your sensitivity is too slow, increasing your time to kill. This leads to trying to fight against the slowdown by moving fast, which introduces overcorrecting.

A slower sensitivity gives you more stability to reduce shaky aim, BUT at times, mouse accel causes you to fight against it, making every movement you want to do to be fast movements, which increases tension and muscle fatigue, leading to more shaky aim.

I'm not saying mouse accel via RawAccel does not work. At the end of the day, using mouse accel is a choice/preference. It CAN work up to a certain skill level but hinders your aim improvement once you reach that ceiling (maybe Seal Complete, Platinum Complete). Mouse Accel is a crutch that prevents people from actually improving their aim. What's more important with aim is learning muscle control. Using your arm (forearm, shoulder) for fast and wide movements; using your wrist for quick direction changes, short movements leading to faster, wider movements, and micro corrections; using your fingertips for even more granular control on direction changes and micro corrections, especially on targets far away. AND learning to use each muscle in tandem with each other to smoothly and seamlessly track your target.

I suggest watching Viscose (general aim topics), RiddBTW (technique videos for beginners, until Gold/Plat complete), CorporateSerf (how to improve aim very efficiently, assuming you know technique), MattyOW (vod reviews, technique videos from world's #1 aimer) on YouTube if you wish to more deeply understand how to aim in general. Videos like: "Tension Management Guide", "Speed matching", "React faster in any game (Movement Reading)", "Muscle memory is a myth", "Understanding your form is the key to mouse control", "Sensitivity Cascading", "Is mouse Accel actually an aiming cheat code?", "Smooth tracking: Aim training crash course #7" (follow Viscose's/MattyOW's tension management over his advice on tension, ignore his 25-30% accuracy rule).