I fight grasses the first year, when I till up an area that was soddy and never gardened before. The following year will find 90% less. I do not like to even use a garden plot the first year, quite honestly. I prefer a full year of cultivation and soil enhancement before use.
Of course, smothering through the use of matting materials, except for a small hole for the plant, works well. I just don't like matting because I like to hoe/cultivate for aeration which matting, it seems to me, prevents. I also do not know how to side dress, mid course, with matting.
Grasses come from root systems or from seed. The seed gets introduced how? The root system grasses are eventually destroyed by cultivation.