Try to buy 10 different yogurts (from a variety of supermarkets and specialty shops) and do a comparison on taste, texture, propensity to de-emulsify, etc. You'll find that there is a very wide range.
And try to reproduce that one great yogurt you had somewhere at home. I mean, I've done the whole comparison above (and many more than 10) in a quest to replicate the yogurt from The Yogurt Shop in Adelaide's (AU) Central Market (which, from what I've been able to find, is the way it is because of a combination of two different yeast strands as well as a specific straining method they use), and I've tried many, many different ways of making yogurt - and still fail to make something like it. I mean, I won't call myself an expert because I don't even have a degree in anything biology or food production related, but I do have enough experience to say that making (good) yogurt is not 'easy' - at least not in the way that it would make sense for people to do it themselves as anything else than a novelty.