All the heavy lifting of figma happens on your local computer. The delta between doing that in a browser in a native app is only shrinking over time.
But I don't think the let's say "other deltas" that are now keeping other high-powered apps from becoming web apps are moving at all. You can check my other comments in this thread for more details, but a specific point I'm making with the original comment is that there are other areas the Figma hasn't dented at all that prevent more powerful apps from being adapted to the browser. And that the fact that design no longer needed those features is what paved the way for its success.
Figma as part of an app family, is way way more similar to Google Slides (i.e., office suite) than it is to Photoshop (i.e., "professional" software).
Digging into my own comment here, part of the reason I harp so much on the skeuomorphic to flat design change is it's such a bizarre thing to happen to an industry, for its defining requirements to change in such a way that the technology gets so much simpler.
E.g., can you imagine if realistic light rendering suddenly was no longer desirable in 3D software? Of course that would leave a gigantic opening for new players!
Once that is true, you want as many people to collaborate as possible and the browser is the perfect delivery model. Plus you ensure a consistent version across all clients.
And liveblocks.io is here to make that happen at scale.
Today the onus is on people who still believe in that idea to express why they think Mighty failed (without falling into the well-worn "year of the desktop linux" trap).
Personally I don't care about the idea either way, I'm just looking at is where the market is going (e.g., how the market share of various software packages are trending). Ideas that sound good fail all the time in the market.
And so far, outside of Figma, the idea you're expressing looks to me like a failure? And personally, I've started to look at other things different about Figma that might have accounted for its success.