I do wonder whether there is a fundamental difference between the video gaming crowd and the pinball crowd. Becoming an expert in a video game is largely a solitary activity. It takes a certain kind of person to be able to spend many, many hours of practice alone. (I don't count things like live chat as real interactions, much the same way as posting here isn't the same as interacting face to face.)
People in the video gaming crowd, on average, are probably more likely to be on the spectrum than people in the pinball crowd. (I used to play video games intensively in the late seventies, and got extremely good at some of them. I do have an obsessive streak, which is definitely an advantage there.) Given that, it's not surprising that there is less interest in fostering new talent or teaching newbies. I mean, how can they, if people are by themselves most of the time?
With pinball, if I want to compete, I have to do it in person and rub shoulders with other people. So, in a quite fundamental way, that's a different setting. My experience has been that, by and large, the pinball crowd here is a friendly bunch. Yes, there are a few elitists around, but most people are helpful and inviting.
Down Under, for many, pinball is as much about the socializing and having a drink as it is about competition. In fact, quite a lot of people don't take the competing too seriously but keep coming because of the social aspect. (Getting a good score in a tournament is bonus instead of a goal for them.)
Another aspect that might play into this is that there is not that much of a "preservation culture" in video gaming. Even very old video games can still be played today, thanks to emulators. And video games don't wear out and break down. With pinball machines, it's much more like being interested in vintage cars. Without other people to exchange tips and ideas (and spare parts) with, things get really difficult quite quickly. The fact that the bloody things break all the time and need fixing in itself fosters more social contact (and, hence, a more caring attitude).
In the end, it really is up to each individual person. If I am the kind of guy who carefully hoards knowledge and tries to discourage others from mentoring, I'm entitled to that. But I'll also pay the social price that's associated with not sharing.
Personally, in the past, I've always been drawn to hobbies where people interact lots and help each other. And, the older I get, the less important winning becomes, and the more important it is for me to put something back into the community. I'm rapidly running out of lifespan. If my life has to have some meaning, I had better pass on some of the things I know because, if I don't, they will be lost.
If you've been driven out of some crowds for trying to share, I'd recommend to simply look for a different crowd, rather than trying to convince the original crowd of the error of their ways. You probably wouldn't succeed anyway, and life is too short to waste on people you don't resonate with.