I agree. That doesn't mean the soil is bad, though. It just needs amendments to increase its porosity.
A few times I have pulled slow-growing seedlings to look at the roots. Every time there was poor root growth. There wasn't only one apparent cause, though. Mostly, it looks like compacted soil, but sometimes there were dry spots in the soil. Every time I was able to put the plants in different soil and grow them to maturity. At this point in my growing experience, I'm sure that root growth is a key factor for seedlings.
I think that's both true and not true. (I know. Difficult logic there.) It's true that the soil can become depleted. But it's also true that it can be revitalized. The challenge is to figure out how to revitalize it. I don't think a general purpose 4-4-4 fertilizer is enough. Other nutrients, like Mg, Ca and other micronutrients also need to be added. The key is to know which and how much.
Agreed. Gardeners and farmers reuse soil for many years. So, soil can be reused.