Because “Have a cigar” doesn’t mean “Have something pleasurable": it an English idiom that mean “Enjoy your success”, or “You succeeded: celebrate it” (by lighting up a cigar). It’s a cognate of the other well know idiom “Close but no cigar”, which means you almost made it, but you didn’t succeed (and you don’t get to light up a cigar to celebrate).

Whereas “Have some fuckin crack cocaine you crack hoe” is just a crass person offering drug to a female drug addict.