It’s really easy to NOT overcook vegetables if you cook them in the microwave. They steam, and the timer turns them off automatically. Before the microwave was in wide use, the revolutionary tool was that petaled steamer that was held above the water in the saucepan, and you couldn’t ignore that puppy, because the pot would boil dry.
If your option for cooking vegetables is to dump them in a pot of boiling water, you can kind of let them go for as long as you need. Boil the broccoli for 20 minutes while you wait for the roast to finish and mashing the potatoes? Why not. Even if you boiled it for 5 minutes and turned the burner off, it would still overcook sitting in the hot water.
My mother-in-law made a version of chicken chow mein that involved dumping chicken, canned LaChoy vegetables, and sliced fresh celery and onions in the “deep well” (like a built-in crock pot) of her stove and letting it cook for hours. The concept of stir-frying was completely foreign (no pun intended!) to her.