The result of philosophical alignment is apparent. We have it and as a result nothing can ever get through the Senate. At least 40 senators will always be in the minority. They will filbuster everything the majority wants to do. When a party is part liberal and part conservative filibusters do not work very well. People always jump ship. The minority DINOs or RINOs always have more reason to jump than the DINOs and RINOs in the majority.
Right now it is the united Democrats filibustering. But if the Democrats get control of the senate and the presidency the Republicans will fillibuster. The result is a government that can do nothing... not even defend itself.
The Democrats were very effective from 1932 until 1968. The Demoratic party back then was made up of liberal northerners and southern conservatives. The northern liberal Democrats under FDR and LBJ used the party loyalty of the conservative southern Democrats to enact the new deal and the great society.
When NIXON did the realignment strategy you espouse, the right came to power but rolled back next to nothing the left had done with a mixes ideology democratic party. Now 35 years later, the leftist agendas of FDR and LBJ have become the centrist norm. And what used to be the right is now expanding on the old leftist agendas.
In california a traditional Old Europe Socialist emigrant is about to take over the Republican party in the most populus state in the nation. He will make it in his image.
Realignment does your homework on voting for you but it also allows the left and the socialist center to rule the United States no matter which party wins.
You can never turn back the clock. The only answer at this point is to move forward and improve the situation in that way, with new ideas. We cannot get rid of Medicare, for example. It just is not going to happen. We can (and some Republicans are) proposing "modifications" of Medicare, to make it more responsive to the market, and less costly to the taxpayer.
People don't want to go back to what they perceive (and which in fact were to some of them) to "the bad old days". But if you can package your ideas so that you are proposing "good new days", that's another matter entirely, and it will get an audience.