I keep saying, they do not call them the stupid party for nothing.
They are not stupid. They are corrupt. There's a difference.
The Republican establishment understands they can win seats in conservative areas by appearing conservative. Meanwhile, they avoid trouble with the Dems, media, and protestors by not opposing the Dems on anything the Dems deem important.
By playing ball, they can also get invited to fun parties, have mistresses, smoke pot, take bribes, etc. They understand the fun stops when they balk the Left.