There are 9 masteries, You referred to a single one. Let's check the others.
- Cleave doesn't allow for more attacks, it is one extra attack from 1 to 17
- Flex damage doesn't increase from 1 to 17, it is just the single die step
- Graze doesn't do more damage, it is always ability mod from 1 to 17
- Nick doesn't allow for more attacks, it is just the single attack without a bonus action
- Sap, well disadvantage doesn't stack. I suppose you could spread out that disadvantage, but when surrounded by four enemies, I'll let you ruminate on the efficacy of spreading your attacks like that.
- Slow specifically prevents you from stacking it, so again, your best way to do so is to spread your attacks to multiple targets.
- Topple, you can't knock a target super-prone, so your only way of improving it is to spread your attacks to multiple targets
- Vex always just gives advantage on your next attack.
So... you literally picked the ONLY mastery that can stack with itself, and tried to say that was the standard for all of them. Where as five of them don't stack or improve at all, and three of them only "improve" by spreading your atacks to multiple targets, which is a tactically poor choice in nearly all instances.