If so, then HOW do you 'decompact' it?

As I can tell so far, the reason for not tilling is to prevent lumps and bumps later on. If there's anothe reason (in addition to weed seeds coming up too) I'd like to hear it.

Also, there must be an alternative to loosen soil ona small scale without a tractor. Maybe a verticutter is the answer...I don't know. Then again, maybe it's good to not have to till for toher reasons as well, because I know my allergies will be horrible if I do.

Tilling also destroys soil structure which requires the worms, insects, bacteria, and fungi to reestablish.

Tilling also wipes out the populations of microbes. Microbes live in their own stratum in the soil. Surface microbes live on the surface. If they get buried they die. Root zone microbes live deep in the soil. When they are exposed to the sunlight and fresh air, they die. When you rototill the soil you mix up all the microbes. The populations are not killed off completely, but they must repopulate before they can be effective in establishing soil structure and in feeding your plants.

Your soil might be compacted but not much. Why? Soil must be pretty wet to become compacted and contractors don't come to work when its raining. What you have is hard soil. The difference is that compacted soil has no air between the particles of minerals. The air gets squeezed out when someone walks or rolls heavy stuff around on WET soil. You can roll stuff around on dry soil for decades and not compact it. Hard soil is hard because it was allowed to dry too much and the beneficial soil fungi living there died off. The soil structure and air pockets are intact, but the microbe population is depleted.

All you have to do to soften hard soil is cover it with 2 inches of mulch (my preferred method) for several months (therein lies the rub). Most people don't want to wait that long. There are surfactants on the market which help the penetration of moisture into the soil. They are very expensive. One of my cohorts on another forum has experimented with them and found they work beautifully. Then he set about duplicating the performance with his own knowledge of chemistry. Once he found the right mix, then I set about getting similar performance using my limited knowledge of chemistry. The result is that you can soften your soil by spraying it with at least 3 ounces per 1,000 square feet of any clear shampoo. My favorite is generic baby shampoo. Spray it once followed by an inch of irrigation. Spray and irrigate again in 2 weeks. You can repeat every 2 weeks from now on if you like. I stopped with the second application and my soil has remained soft (when moist) for about a year now. Frankly, I was very surprised that this method worked and worked so fast.