http://pnwdistrict.org/pdf_files/Diseases of Roses.ppt#1

At least they did note that Roundup damage can mimic Rose Rosette Disease, which is something.

PS: if my comment is seen as being unnecessarily negative, I can understand that, but after fifteen years of lugging around hundreds of gallons of fungicide on my back just to keep my roses looking "healthy" (as opposed to actually being healthy), I have taken a rather dim view of the whole "better living through chemistry" paradigm of rose cultivation. (and no, I don't do the spray thing anymore) If you can't grow in my garden without fungicide and pesticide dumped on you every 10 days, you ain't welcome in my garden!

Of course, the choice should always be available, there are some varieties of roses which are beautiful but high maintenance, but all of us have people, critters, or things in our lives from time to time that are high maintenance.
But I'm venturing a guess that there may be some lobbying going on by special interest groups, i.e. huge powerful conglomerates that include chemical companies which produce pesticide, as well as perhaps rose vendors who sell varieties susceptible to bugs and blackspot to account for the slides.

It's all about choice, but both sides, spray and not spray, in my opinion, should be represented and it is the individual rose grower that should make her choice. The choice should not be made for her (or him) by not providing enough info to make an informed decision.

Although I no longer use fungicides on my roses, I am absolutely not going to tell anyone else they shouldn't use them. That is not my place. If a person wants a garden full of modern styles and they want immaculate foliage, that is their choice, and in many parts of the world the only way to accomplish that is by using fungicides. I used to have a gorgeous archive of the Ralph Moore roses (about 350 varieties) and this was a spectacular display in the garden, but it required a non-stop barrage of fungicides from April through October (although I could get away with doing it less often during July and August) in order to remain looking healthy, and to keep the plants performing to their potential. Now that I no longer use fungicides on them, they have almost all dwindled to sad plants 1/4 their size, bloom quality is severely diminished, and few of them keep their foliage for long. Because of this I have decided to decommission the collection this coming spring. I'm sad to be letting them go, but I won't get that sprayer out again.