Because we still had a kkk member, Robert Byrd, run and win on the Democrat ticket. You know, Hillary Clinton’s mentor.
So what was the role of Nixon‘s southern strategy?
"From now on, the Republicans are never going to get more than 10 to 20 percent of the Negro vote and they don't need any more than that... but Republicans would be shortsighted if they weakened enforcement of the Voting Rights Act. The more Negroes who register as Democrats in the South, the sooner the Negrophobe whites will quit the Democrats and become Republicans. That's where the votes are. Without that prodding from the blacks, the whites will backslide into their old comfortable arrangement with the local Democrats."
-Kevin Phillips, chief campaign advisor to Richard Nixon and senior GOP political strategist, 1970
Of course, the strategy was continued with future Republican administrations, as shown in this interview with Lee Atwater, chief campaign advisor to Ronald Reagan and senior GOP political strategist, in this interview from 1981:
Atwater: As to the whole Southern strategy that Harry Dent and others put together in 1968, opposition to the Voting Rights Act would have been a central part of keeping the South. Now [Reagan] doesn't have to do that. All you have to do to keep the South is for Reagan to run in place on the issues he's campaigned on since 1964 [...] and that's fiscal conservatism, balancing the budget, cut taxes, you know, the whole cluster...
Questioner: But the fact is, isn't it, that Reagan does get to the Wallace voter and to the racist side of the Wallace voter by doing away with legal services, by cutting down on food stamps?
Atwater: Y'all don't quote me on this. You start out in 1954 by saying, "Nigger, nigger, nigger." By 1968 you can't say "nigger"—that hurts you. Backfires. So you say stuff like forced busing, states' rights and all that stuff. You're getting so abstract now [that] you're talking about cutting taxes, and all these things you're talking about are totally economic things and a byproduct of them is [that] blacks get hurt worse than whites. And subconsciously maybe that is part of it. I'm not saying that. But I'm saying that if it is getting that abstract, and that coded, that we are doing away with the racial problem one way or the other. You follow me—because obviously sitting around saying, "We want to cut this," is much more abstract than even the busing thing, and a hell of a lot more abstract than "Nigger, nigger."
en.wikipedia.org