Biden has had several different credible claims over the years, but they were all swept under the rug, or given the same excuses the GOP gave for Trump.
It’s literally only the past few years where people pretended to care and action has been taken, and only a few people have really been punished for it.
The frightening thing about rape culture is that this is the moral calculus that it relies on to stay alive. There's always "more important things", always something more "serious" to prioritize. And when rape culture is at its most powerful, it is always its victims that are thrown under the bus first.
It is a complicated issue in general. You're right, politics are often at play to sweep the whole thing under the rug under certain pretenses that are mostly convenience. A lot of the problem is also the fact that we're just NOW relatively recently been more mindful, society-wise of the idea of inadequate interaction and being mindful of other's physical space and the idea of consent applied to certain gestures.
The things that Biden did that were fairly questionable and under scrutiny rightfully so, were common back in the day. Back then nobody really batted much of an eye regarding kissing, and touching the way he did so long as it wasn't touching private parts (then again the understanding of power dynamics and how a person of certain status is "allowed" to get away with things like these was also a lot stronger back then than it is now, so it is likely a bad mix of "this is ok" and "better not to say no to these overlords").
People like Epstein and Weinstein while being very powerful men on their own right, also got hauled for really hardcore stuff, like active sexual exploitation and even pedophilia. It is also possible that in the eyes of some investigators what Biden did pases muster as a sort of "yeah ok, maybe he did this, but it isn't too much of a biggie......", not a posture I agree with btw if it actually does occur.
There is fundamentally a lot to still do society-wise to keep pushing and dealing with this phenomenon, so it gets the deserved attention and so it doesn't get swept under the rug under certain pretenses, concepts like unwanted touching and trespassing one's physical boundaries along with the MeToo movement, gained relevance because it was a sort of an awakening of something we had internally normalized that ultimately turned out was really not ok, and it is something that needs to keep on evolving.
Here is a video that talks about it, which I found insightful