"Specialized subset of designers and engineers share skill-base."
OP also misses the other side of the coin: design-lead tools like Bootstrap have made it much easier for engineers to design great looking apps.
It's convergence, not competition.
Except that it actually is adequate, a lot of the time. Much like your 'designer-as-engineer' code is often adequate.
Same coin, different sides.
using a css framework has nothing to do with design, it's an implementation detail. using a preconfigured theme doesn't make it designed (for sure doesn't make it designed well).
//edit: reworded it.
But, for the sake of discussion between rational people, we should bypass excessive pedantry.
EDIT: -- I see the comment above was modified to add the emphasis and ", it's an implementation detail..."
Please don't fixate on the one example provided. It's a tool that greatly aids design. Starting up a Heroku instance with a CMS isn't engineering either, but that's Not The Point.
me arguing your opinion about programmers <air quote>designing</air quote> <air quote>great looking</air quote> apps is not pedantry nor is it irrational. better tools are there to make you work faster, they don't make you work better.
But one side of this argument seems to be blind to the obvious parallels.