It raises the threshold to get into the game, but makes it go faster once you grasp the general principles. Not just the Attack trait, but the way traits are used in general.Actually for me this is the opposite. It's an example of a consistent rules grammar resulting in less rules checking.
Once I get to know how the 'Attack' trait works, I no longer need to look up whether or not something has MAP, what it targets, and a host of other things.
This is different from how 5e works, where each bit of rule (spells, feats, etc.) usually has all the relevant bits as part of its own description, instead of inheriting them from somewhere else.