Agreed there is a whole heap of synth in the background of a load of these tracks, but playing them live even in a 3 piece is entirely possible - the crowd will vibe off what you give them and won’t moan there was no synth.
There are a load of synth guitar pedals out there to help with this, especially if you have 2 guitarists but I think drummers have to get on board with sample pads hooked up to the PA so they can trigger synth/samples/atmospheric sounds whatever.
But as some of the guys have said, it’s a willingness for people to move out of 3 bar blues etc.
Keys help, but there is loads that can be done without