Adding an even blend of oil and vinegar mixed with the necessary sweet, salty, and savory components after cooking helps maintain the texture of your cooked vegetables.
When vegetables are roasted in a high-degree oven or cooked in a skillet with some oil, caramelization occurs, meaning their natural sugars are released through the heat.
If you marinate vegetables before cooking, you don't have that cooked outside barrier to prevent your marinade from potentially altering the structure of your vegetables.
By adding a flavorful sauce or marinade post-cooking, you can leave it on your vegetables until you decide to enjoy them without worrying about their texture being compromised.
If you have leftovers, they are guaranteed to taste better after soaking in the marinade for a day or two, and you can use them to elevate salads or an oven-baked chicken breast.