5E builds a character out of shopping. Species, class, subclass, feats, a background that hands you tools like party favors. By session one, you are already a brand. The sheet is a catalog.
ACKS builds a character out of a few choices that have to last.
Proficiencies are the quiet system people skip when they bounce off the book. They are not feats. They are not a second class. They are the difference between a fighter and this fighter: the one who can ride, bargain, siege, or keep a ship from killing the party before the orcs do. You do not get a new personality every three levels. You get a small number of things you are actually trained to do, and later a few more if you study.
That limit is the point. A character with four extra slots still has a shape. He is not good at the whole Renaissance. He is good at the work that kept him alive long enough to matter. When the campaign turns toward domains, markets, and war, those picks stop looking like garnish. They look like a résumé.
I spent a year on sheets that were louder and less specific. Everyone could do a bit of everything if the subclass said so. Nobody felt like a person with a trade. ACKS will let you make a bland adventurer. It will also let you make a captain, a forger, a court rat, or a wilderness case without adding a new hardcover.
Do not collect proficiencies like stamps.
Pick the ones you are willing to be known for when the gold runs out, and the map starts asking who you are.