In light modes, I find that variations gray and bolding certain symbols, variable names, function names in definitions and method calls to be enough.
Just enough hint so the brain can skim for the matching information. My editor highlights the opening and closing brackets of my current block,but indent level indicators are usually enough for me to visually validate.
Dark modes make contrast more difficult to discern though.
Back in the late 2000s and early 2010s Google and Facebook supported XMPP, so you could login to Facebook Chat / Google Talk via Pidgin through an XMPP gateway (if if this was the default protocol or a bridge I'm not sure, its been years).
The biggest strength I see for XMPP is that because the web and even enterprise (think banking etc) uses XML too, everyone's optimized the ever living crud out of HTML so you could get some very high performance libraries to churn through all those stanzas, but also more importantly, its an extensible protocol. There's no reason it cannot have half of the things that exist on Discord, without disrupting the protocols OOTB design, because unlike IRC and other competing protocols, its extendable by design.
My favorite example - Arista network switches can be clients on an XMPP server. Control plane's have to be very slim. XMPP enables someone with a network operator to apply wide, symmetrical configurations across a network, without repetition. You can add the "core" switches to a group chat, and query them for information simultaneously.
Found an example article: https://jonw.mayhem.academy/arista-switch-wrangling-with-xmp...
You would never see Discord as a control plane management option, nor a Slack, Telegram or Signal option. But if all or a group supported XMPP, there would be a low resistance avenue for that (if someone really wanted it).
As it stands, we have product lock in due to each service having it's own system, with limits on interactivity. So I won't be cross-channel quoting outage causes directly from the switch in the company Slack any time soon.