In my opinion, making such generalizations is not a path I'd want to follow. Yes, it is true that not all plants do well in all places. Yes it is true that some breeders test their plants in different climates before they distribute them, while others don't . And yes, it is true that some sell plants much more ethically than others. But there is merit in many old classics and there is merit in many of the new cultivars out there too. As a grower, I choose not to keep plants that do not perform well in my garden here for very long. The non performers have a 3 year max and then they're out of here. But if something doesn't do well, the first questions I always ask myself are, "Is this plant not thriving because of something in the environment here - is it getting enough water, enough sun, enough room to grow, is the soil good, etc.?" And if I feel the plant hasn't been given a fair chance, maybe it is getting too much shade, then it gets moved to a better spot before I'm ready to toss it out with the dishwater.
There are several newer hybridizers on the scene that I buy from regularly whose plants have proven themselves to be excellent, vigorous and hardy performers in my garden and those are the ones I'll continue giving my plant $$ to. There are also several who will never get my business again. There are some whose plants I really like, but I've learned ( the hard way) that many of their plants are just too tender or too evergreen to thrive here. That is not to say that those same plants wouldn't do beautifully in a more southern climate. I find it helpful to look first at hybridizers plants when they are breeding in close or similar climates to where my garden is, or to look at plants that perform beautifully in club gardens or regional tour gardens.
Good luck with your growing!! Many of the Florida growers I know ( who are not commercial growers) say they have to use sunken pots in their gardens to have much success growing there. This is only anecdotal information given to me by people who live there, as I have only observed, never grown daylilies in FL.
