Never be discouraged by comparing what you grow and what you see at the garden center. Those plants have been "pumped" to encourage sales. And, there's not a whole lot more value beyond that.
The varieties are often chosen on the basis of their visual appeal at a very early age - not their productivity in the garden or taste at the table. Fertilizer has been injected into the water that flood those seedling, every day. Greenhouse conditions are carefully controlled. Hereabouts, even light is supplemented.
If their plants begin to get "rangy" - the greenhouse growers will spray them with a growth-retardant.
Finally, these hot-house creatures show up at the garden center where they had better be gone in a matter of hours. Otherwise, they begin to show the results of the suffering from the move outside their pampered environment.
Your own plant starts can make the move outdoors more easily, and be more healthy and more productive in the garden. They can be in enormously greater variety and have more personal appeal than anything - anything - you can get at the garden center.
Steve