I think most people start out with hatchery birds - they are easily accessible and when you don't have connections or know how to find better quality birds, it is easy to place an order or buy during chick days from the feed store. We've all done it and some of my hatchery birds are personal favorites for sentimental reasons. Many people go their whole lives with only hatchery birds and if all they want is a few eggs for their table, they'll be perfectly happy.
Once I learned more and researched a lot, I too decided no more hatchery birds for me. Although I've been lucky with mine - the only health issue I've had with a hatchery bird was a 2-year-old hen with a vent prolapse - health issues are more likely because hatcheries don't take a lot of care in their breeding practices. Not to mention they're not always completely honest about their birds. What they sell as purebred often has leghorn mixed in because leghorns are sensational layers and what most people want are lots of eggs.
What completely sold me was visiting a guy who has bred heritage barred rocks in a line that goes back over 100 years. The visual difference in them - their size and barring - compared to the hatchery barred rocks I had in my flock, was astounding. But I was even more surprised when I brought home a few of his birds and found their temperament to be so completely different it was hard to believe these were nominally the same breed. Hatchery BRs have a reputation for being bossy and none-too-friendly for the most part. The heritage BRs are calm, quiet, gentle and kind. If there is a scuffle between hens, the heritage BRs are simply NEVER the problem.
What annoys me most about hatcheries is they categorize them as "layers" "meat" or "dual purpose" but the reality is that all hatchery birds are built to be either egg layers or ornamental. A BR is technically a dual purpose bird, yes, but by the time hatcheries have diluted the genes by adding in leghorn to make them better layers, they've also reduced the size and made them too scrawny to be used as a meat bird. Same with every other dual purpose breed they touch.
If you truly want dual purpose breeds - you have to get them from a reputable breeder who is breeding to maintain their true and intended characteristics.