Figma is sort of an Apollo Project among webshit, isn't it? IIRC they did rather extreme amount of R&D to make the webapp performant in spite of the web as a platform. Great that they did, and I hope their insights will keep trickling down to everyone else - but I don't think they're currently an example anyone can actually follow.
It’s great, but it’s not Apollo-level anything. Most games are far more interactively and visually complex. Apples to oranges with UX and interaction problems to solve, but certainly not depth and complexity. I’ve certainly experienced bugs in Reddit’s interface before — there seems to be this idea that they have to be so risk averse that they can’t do anything significant— I’ll bet you a pizza that their official app which implements all the features that people really want to use is made with JS/HTML on the back end anyway.