It has a effect for sure but it's hard for me to say. I grew up with forums but I found most of them I used to interact with too small and slow in terms of news flow and quantity of content before I found GAF which was basically my sweet-spot, I always had something new to read when I wanted to but it was also easy enough to follow what I wanted to follow. Now Era pretty much is the same to me and I love it here for the same reasons plus the notification-system makes things even easier.
I don't like Reddit all that much, the idea is great but the execution is not for me. The upvote and sorting system still feels confusing to me after many years and even sorting comments with "New" instead of "Top" sill makes things feel like a disjointed mess and it's hard to follow things. To me Reddit also feels really impersonal for whatever reason as if any poster is just a random name while here on Era I have a much easier and better time remembering people and actually feel connected to them.
As for Discord, I love it in theory, so many people, so much content and input and always something to do, read or reply, but yeah that's only the theory. I am member in over a dozen of servers because I would have a legit use for them all but I barely interact with any of them out of fear to miss anything. Discord moves so fast, when people talk to you they often won't use @-mentions so you have to keep track of everything manually which becomes really stressful and, for me atleast, it often feels like work. It's a shame because I'm a member of so many great communities there I just have no idea how to keep up with them without it requiring a ton of free time :/ (And I also hate how Discord is forced to be only one window, let me have servers and DM chats in their own window if I want to, it would atleast help a little bit)
I do not want boards like Era and wikis to go anywhere and hope they can eventually keep their footing and co-exist with Discord. Both have their merits and it would be a shame if message-boards and wiki's fully disappear for the sake of "progress" when they actually can supplement each other pretty well if done right.