There's alot of issues with overcrowding your vegetables and not just with soil but you will increase everything bad - fungus, disease, rot, insects, wet plants, wilt, inproper drainage, air
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Plant Viruses: Soil‐borne
Blight doesn't die after two years. This is incorrect. Hypothetically blight should die after the plant dies but they winter on debris and the cycle continues. It's virtually impossible to get rid of all the infected debris as it hides in the soil and has likely spread outside your garden. Rotating is a small measure of prevention but it wont prevent blight either because it often gets carried into soil by winds from neighbouring soils.
Basically if you are new to gardening and live in a typcal climate with cycles of moisture and humidity during the growing season you want to avoid overcrowding your plants if possible. Even if you live in dry climate the problem with this method will still come when you water the garden as most water distribution will occur from the top down straight onto the leaves and trickle down to soil. This is a fungus, wilt and filtration issue waiting to happen. You could possibly get away with narrow crops such as lettuce that you will trim often but It's still going to be finicky trying to control the weeds when you have such narrow pathways between for maintenance.
You could however tarp the soil with plastic crop cover which we do alot in agri farming in Korea. Im just saying this isn't a very easy method to manage as a beginner gardener and invites alot more issues than if you had just planted less crops and spaced it out. If you don't have a ton of time to invest and manage a garden everyday I highly recommend not doing this method imo. If space is at issue look into building some kind of way to espalier your leaf and fruit crops to hang from pots and grow out vertically and keep bulb crops for the ground.