I hate Slack and I particularly despise Gitter. All the communities I had to go on at one point were totally out of service or totally uninterested in helping newbies. I am glad some organizations still use IRC as their main online network.
^ :-)
On slack and Gitter they are often focused on work, on getting things done, so they really don't care about users or new developers and their problems which are unrelated to the project. And this is good, because everyone needs a channel where they can focus on getting things done.