It totally makes sense that you get N loop calls, how else is it going to guarantee proper stepping through an animation without elapsed. Variable vs fixed frame rate animation is kind of basic game dev stuff and really I don't see why one would want to use the fixed rate animation system when the intervals are too close to the frame rate or worse consistently below.
If your timing is clearly longer than typical frame rate, the animation system should always be better. If you are at the order of frame rate variation though, the animation can be worse, because you have no elapsed, hence no notion how far to skip in a time-adaptive algorithm, and you may enter OnLoop more than once per rendering, which clearly is suboptimal. That's how I would read the comments in the XML though it's phrased differently.
The second thing is that it seems like the animation system is decoupled from the rendering timing, which could additionally take some peakiness out of the whole thing because even diverting timers are less likely to overlap due to being bundled up within one OnUpdate.