Experienced gardeners use raised beds to sidestep a long list of gardening challenges.
The primary purpose of using raised beds is to grow in a custom soil mix because your soil is poor. The raised bed soil is lighter, fluffier, and contains more water and nutrients.
Lousy soil is out because you fill a raised bed with a customised soil-and-compost blend. Greater exposure to the sun warms the bed, allowing more plant diversity and extending the growing season. Plants can be closer together, so yields go up, water-use efficiency maximises, and weeds are crowded out.
Finally, raising the soil level by even 20 cm reduces the back-bending effort needed for jobs such as planting, weeding and harvesting.