Accessibility also refers to the hardware & network speeds of the users machine. Discord is a heavy web app (that also pings back a lot of analytics) with users actively using ‘heavy’ features like sending videos. It’s also subject to US sanctions or internal bans where entire countries can be blocked or do the blocking. Speaking of blocking, Discord could block a community member for a non-community-related reason (or by mistake) & there will be no way to resolve it since the community is not in control of the server.

Free as in gratis, sure. But as in libre? No, it’s definitely proprietary & it’s free because users are the product (data collected and upselling Nitro); not every user wants to give up their privacy freedoms to participate. Discord’s not federated so users will be required to create an account & agree to the ToS & CoC of Discord, not the community running it. Discord has also been hostile towards folks trying to make alternative clients to meet usability needs & certain kind of bots.

Without IRCV3 & bouncer it would be a difficult/unexpected experience for a new user. Luckily IRC isn’t the only libre option. If you want to keep the system requirements low XMPP MUCs are good & allow federation. If you want newer bells & whistles at the cost of system requirements federated Matrix can be considered (tho centralization concerns around Matrix.org having the most users, most used server, most used client, & controls the spec). There are bridges between all of these that you can choose as many or as few as meets the community needs such as a community-hosted XMPP main server in a neutral country with bridges to IRC & Discord.