I've heard the word used both ways, and as most people have mentioned, I've noticed that in Spanish, the word is more closely aligned with being slang for any premium cigar, (if it ever had anything to do with the composition of the cigar, it probably became generic because until very recently the majority of quality cigars available in Latin America were puros), whereas in American English, since most cigars on the U.S. market have been blends ever since the embargo, manufacturers have recently started using the word in a more specialized sense in order to sell the relatively new concept of high quality pure Nicaraguan or Dominican cigars. It would be interesting to see just when exactly this use of the word started showing up, but I'd venture a guess and say during the 90's boom.
While Drew Estate was using the word correctly in the traditional Spanish sense of the word, in the current U.S. market it is a bit duplicitous to use it that way, because while the rest of the world still thinks a puro is just a cigar, the American market they're selling it in has a much more specialized definition of the term. Just as you'd get two different things asking for a "rubber" in America or Australia, a "puro," means different things to different people. This is just another example of how every manufacturer in the world uses the same God damned terms to mean completely different things, such that one brand's Toro is another brand's Churchill is another brand's Robusto. It's a maddening smokescreen of hype and marketing-babble for any newb to unravel.
