Violets are native, and usually grow thickly enough to prevent anything else where they are. That's always impressive & can be very helpful under taller entities, or any spot you want to fill and not worry about having many unintentional sprouts of anything else showing up. Violets are also tough enough to be a moderately-used path, in lieu of something much more expensive like mulch or some kind of pavement, and has great value to wildlife, as mentioned.
Not every individual of a native species is welcome where it might be, like hundreds of acorns sprouting in a bed under an oak tree, but a native can't invade its' own territory, and therefore can't be a weed. No gardener keeps an unwanted plant though, good luck getting it like-you-like-it.
If there are entire sections with no plants you want to keep, you can smother everything under cardboard (thick, corrugated stuff, overlapping seams well,) covered with mulch, then add desired plants next year. The cardboard should have decomposed and the mulch will have begun to improve the soil dramatically in those spots. Mowing before laying the cardboard will help it be able to lay flat against the ground. I'd do it w/o the bag, all of that chopped-up plant material under the cardboard would be such an excellent start/addition to the action of the smothering, as well as being green under the brown cardboard, a perfect match. Smothering has always been much more effective for me for starting with a blank slate than trying to dig stuff up. Too many seeds sprout that way.
