How do we remove the hostility and radio silence for cryptocurrencies which are not bitcoin on this site?
The answer to that is not new: to change this, we'd need more contributors taking an active interest in these topics.
It seems this sites scope is currently about all crypto currencies. If this is the case, is it possible to open the minds of the hostile ones, so they can look past their personal opinions and just help?
Yes, the scope of the site includes other cryptocurrencies. However, that doesn't mean that any individual contributor is obligated to volunteer time answering questions they are not personally interested in.
It's a bit of a catch-22: we don't seem to have a critical mass of users that are interested in maintaining and answering questions about altcoins, so in turn no new contributors for that content are lured in, which in turn means that there are fewer interesting questions to entice competent answerers.
Frankly, this would be solved if every altcoin had one or two contributors that subscribed to the relevant tags and edited/answered every corresponding question such as e.g. Rene Pickhardt has been doing for Lightning Network questions lately.
I and probably others as well have spent time advocating this to altcoin communities, yet the situation has not improved: most altcoin questions still get really low engagement, don't get cleaned up, and also don't get good answers.
In a weaker form, the situation could even be helped, if bad questions in general got culled more effectively, so that any interested party looking at unanswered questions in these tags would not see a heap of trash. So, in a twisted way, altcoin questions getting more scrutiny might actually be working in favor of altcoin questions (although maybe not in your specific case).
Would it be worth creating a new SE site called cryptocurrencies.stackexchange.com where it becomes obvious that the site is about all cryptocurrencies and changing bitcoin.stackexchange.com to only be about bitcoin to make it easier for people to understand the scope?
This has been proposed multiple times in the past, and a few attempts to start a new SE in Area51 had been taken. One of the reasons this didn't succeed was because Bitcoin.SE was covering that topic.
However, the combination of narrowing the topic of Bitcoin.SE to Bitcoin-only and starting a Cryptocurrency.SE has not been tried before. I could see this getting support from both Bitcoin and altcoin proponents. It might be that the time for this idea has come.
