There are more problems with hatchery birds than just not looking like the standard very much.
Hatchery birds are bred for egg production - to make hatchery birds. Egg production is not the same thing as going broody and raising chicks. Many breeds from hatcheries do not any longer, go naturally broody. Hatchery lined pullets/hens do also often suffer in the long term from becoming eggbound and die early - again because they were bred more to produce tons of eggs over short lives rather than a naturally productive lifespan.
Hatchery birds are not bred for temperament, since no one actually has to live with them, they're caged til they die. You can get some fairly hard to deal with animals if the breeder never has to actual deal with what he's producing.
That said. I have started with hatchery birds. Some actually went broody - really atypical for partridge rocks from hatcheries. I got TWO groups of 25 chicks - and culled them all before I did get a good group from Ideal. Of those 8 hens and two roos were worth keeping.
They did lay well, some went broody and did raise chicks. But they are smallish, their colors are poor, their egg color not exactly brown eggs, more very light tan and I didn't like the quality of the chicks they produced.
I'm selling them all. I got breeder delawares from eggs, and some young roosters from heritage lines and immediately saw a difference in size, type and over all quality, I also got hatchery dels for comparison. I culled all but two of the hatchery dels - too small, too poor in type. The breeder dels lay huge pink/brown eggs, are proper in size and type. The hatchery dels are smaller, lay smaller eggs, are more flighty.
There are some drawbacks to hatchery birds for the home flock depending on what you want and how seriously you want to cull, and what you are willing to accept in things like temperament, size, life span, even egg color.
They're fine for a start, to get a feel for what you do want. Don't be surprised if it changes over time. You learn what you can and can't live with.
I'm kinda picky. And egg color matters in sales of eggs, though I don't do a lot - I find people prefer the better colors.
And I LIKE a vividly colored egg better, they're more interesting. I also like a good sized bird in a dual purpose breed and you really won't get that from hatchery stock.